Circadian rhythm and light

قَالَ مُوسَىٰٓ أَتَقُولُونَ لِلۡحَقِّ لَمَّا جَآءَكُمۡۖ أَسِحۡرٌ هَٰذَا وَلَا يُفۡلِحُ ٱلسَّٰحِرُونَ

Moses said, ‘Is this what you say about the Truth when it comes to you? Is this sorcery? Sorcerers never prosper.’

فَلَمَّا جَآءَ ٱلسَّحَرَةُ قَالَ لَهُم مُّوسَىٰٓ أَلۡقُواْ مَآ أَنتُم مُّلۡقُونَ

When the sorcerers came, Moses said to them, ‘Throw down whatever you have.’

فَلَمَّآ أَلۡقَوۡاْ قَالَ مُوسَىٰ مَا جِئۡتُم بِهِ ٱلسِّحۡرُۖ إِنَّ ٱللَّهَ سَيُبۡطِلُهُۥٓ إِنَّ ٱللَّهَ لَا يُصۡلِحُ عَمَلَ ٱلۡمُفۡسِدِينَ

When they did so, Moses said, ‘Everything you have brought is sorcery and God will show it to be false. God does not make the work of mischief-makers right

وَٱتَّبَعُواْ مَا تَتۡلُواْ ٱلشَّيَٰطِينُ عَلَىٰ مُلۡكِ سُلَيۡمَٰنَۖ وَمَا كَفَرَ سُلَيۡمَٰنُ وَلَٰكِنَّ ٱلشَّيَٰطِينَ كَفَرُواْ يُعَلِّمُونَ ٱلنَّاسَ ٱلسِّحۡرَ وَمَآ أُنزِلَ عَلَى ٱلۡمَلَكَيۡنِ بِبَابِلَ هَٰرُوتَ وَمَٰرُوتَۚ وَمَا يُعَلِّمَانِ مِنۡ أَحَدٍ حَتَّىٰ يَقُولَآ إِنَّمَا نَحۡنُ فِتۡنَةࣱ فَلَا تَكۡفُرۡۖ فَيَتَعَلَّمُونَ مِنۡهُمَا مَا يُفَرِّقُونَ بِهِۦ بَيۡنَ ٱلۡمَرۡءِ وَزَوۡجِهِۦۚ وَمَا هُم بِضَآرِّينَ بِهِۦ مِنۡ أَحَدٍ إِلَّا بِإِذۡنِ ٱللَّهِۚ وَيَتَعَلَّمُونَ مَا يَضُرُّهُمۡ وَلَا يَنفَعُهُمۡۚ وَلَقَدۡ عَلِمُواْ لَمَنِ ٱشۡتَرَىٰهُ مَا لَهُۥ فِي ٱلۡأٓخِرَةِ مِنۡ خَلَٰقࣲۚ وَلَبِئۡسَ مَا شَرَوۡاْ بِهِۦٓ أَنفُسَهُمۡۚ لَوۡ كَانُواْ يَعۡلَمُونَ

and followed what the evil ones had fabricated about the Kingdom of Solomon instead. Not that Solomon himself was a disbeliever; it was the evil ones who were disbelievers. They taught people witchcraft and what was revealed in Babylon to the two angels Harut and Marut. Yet these two never taught anyone without first warning him, ‘We are sent only to tempt- do not disbelieve.’ From these two, they learned what can cause discord between man and wife, although they harm no one with it except by God’s leave. They learned what harmed them, not what benefited them, knowing full well that whoever gained [this knowledge] would lose any share in the Hereafter. Evil indeed is the [price] for which they sold their souls, if only they knew

وَجَآءَ ٱلسَّحَرَةُ فِرۡعَوۡنَ قَالُوٓاْ إِنَّ لَنَا لَأَجۡرًا إِن كُنَّا نَحۡنُ ٱلۡغَٰلِبِينَ

The sorcerers came to Pharaoh and said, ‘Shall we be rewarded if we win?’

وَأُلۡقِيَ ٱلسَّحَرَةُ سَٰجِدِينَ

The sorcerers fell to their knees

(And follow that which the devils falsely related against the kingdom of Solomon�) [2:102]. Muhammad ibn 'Abd al-'Aziz al-Qantari informed us> Abu'l-Fadl al-Haddadi> Abu Yazid al-Khalidi> Ishaq ibn Ibrahim> Jarir> Husayn ibn 'Abd al-Rahman> 'Imran ibn al-Harith who said: �Once as we were sitting with Ibn 'Abbas when he said: 'The devils used to eavesdrop on heaven. One of them would bring a word of truth from therein, and when he is trusted for telling the truth, he would add to it seventy lies with which he earns the hearts of people. When Solomon came to know about it, he took it and buried it beneath his throne. When he died, a devil stood in the street and said: 'Shall I guide you to Solomon's guarded treasure, the like of which he does not have?' They said: 'Yes, do'. He said: 'It is under his throne; go and unearth it'. They said: 'This is magic'. Different nations then copied it f

And they follow wa’ttaba‘ū is a supplement to nabadha ‘it cast away’ what the devils used to relate during the time of Solomon’s kingdom in the way of sorcery it is said that they the devils buried these books of sorcery underneath his throne when his kingdom was taken from him; it is also said that they used to listen stealthily and add fabrications to what they heard and then pass it on to the priests who would compile it in books; this would be disseminated and rumours spread that the jinn had knowledge of the Unseen. Solomon gathered these books and buried them. When he died the devils showed people where these books were and the latter brought them out and found that they contained sorcery and said ‘Your kingdom was only thanks to what is in here’; they then took to learning them and rejected the Scriptures of their prophets. In order to demonstrate Solomon’s innocence and in repudi

And the sorcerers came to Pharaoh saying ‘Surely a-inna read pronouncing both hamzas or by not pronouncing the second one but inserting an alif between the two in both cases there will be a wage for us if we are the victors?’

And the sorcerers fell down in prostration.

And so the sorcerers came to Fir'awn. They said: "Indeed there will be a (good) reward for us if we are the victors. (113)He said: "Yes, and moreover you will (in that case) be of the nearest (to me). (114) The Magicians convene and change Their Ropes into Snakes before Musa Allah describes the conversation that took place between Fir'awn and the magicians he collected to defeat Musa, peace be upon him. Fir'awn told them that he will reward them and give them tremendous provisions. He made them hope in acquiring what they wished for and to make them among his private audience and best associates. When they were assured of the cursed Fir'awn's promises,

And We revealed to Musa (saying): "Throw your stick," and behold! It swallowed up straight away all the falsehood which they showed (117)Thus truth was confirmed, and all that they did was made of no effect (118)So they were defeated there and returned disgraced (119)And the sorcerers fell down prostrate (120)They said: "We believe in the Lord of all that exists (121)"The Lord of Musa and Harun. (122) Musa defeats the Magicians, Who believe in Him Allah states that at that tremendous moment, in which Allah differentiated between Truth and Falsehood, He sent a revelation to His servant and Messenger Musa, peace be upon him, ordering him to throw the stick that he held in his right hand, فَإِذَا هِيَ تَلْقَفُ (It swallowed straight away) and devoured, مَا يَأْفِكُونَ (all the falsehood which they showed.) the magic that they caused the illusion with, of magic with which they caused m

حَدَّثَنَا أَبُو نُعَيْمٍ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنِ الأَسْوَدِ، قَالَ سَمِعْتُ جُنْدَبًا، يَقُولُ اشْتَكَى النَّبِيُّ صلى الله عليه وسلم فَلَمْ يَقُمْ لَيْلَةً أَوْ لَيْلَتَيْنِ‏.‏

Narrated Jundab:The Prophet (ﷺ) became sick and did not get up (for Tahajjud prayer) for a night or two

حَدَّثَنَا ابْنُ مُقَاتِلٍ، أَخْبَرَنَا عَبْدُ اللَّهِ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ هِنْدٍ بِنْتِ الْحَارِثِ، عَنْ أُمِّ سَلَمَةَ ـ رضى الله عنها ـ أَنَّ النَّبِيَّ صلى الله عليه وسلم اسْتَيْقَظَ لَيْلَةً فَقَالَ ‏ "‏ سُبْحَانَ اللَّهِ مَاذَا أُنْزِلَ اللَّيْلَةَ مِنَ الْفِتْنَةِ، مَاذَا أُنْزِلَ مِنَ الْخَزَائِنِ مَنْ يُوقِظُ صَوَاحِبَ الْحُجُرَاتِ، يَا رُبَّ كَاسِيَةٍ فِي الدُّنْيَا عَارِيَةٍ فِي الآخِرَةِ ‏"‏‏.‏

Narrated Um Salama:One night the Prophet (ﷺ) got up and said, "Subhan Allah! How many afflictions Allah has revealed tonight and how many treasures have been sent down (disclosed). Go and wake the sleeping lady occupants of these dwellings up (for prayers), perhaps a well dressed in this world may be naked in the Hereafter

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنِ ابْنِ شِهَابٍ، أَنَّ عُمَرَ بْنَ عَبْدِ الْعَزِيزِ، أَخَّرَ الصَّلاَةَ يَوْمًا، فَدَخَلَ عَلَيْهِ عُرْوَةُ بْنُ الزُّبَيْرِ، فَأَخْبَرَهُ أَنَّ الْمُغِيرَةَ بْنَ شُعْبَةَ أَخَّرَ الصَّلاَةَ يَوْمًا وَهْوَ بِالْعِرَاقِ، فَدَخَلَ عَلَيْهِ أَبُو مَسْعُودٍ الأَنْصَارِيُّ فَقَالَ مَا هَذَا يَا مُغِيرَةُ أَلَيْسَ قَدْ عَلِمْتَ أَنَّ جِبْرِيلَ نَزَلَ فَصَلَّى، فَصَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم ثُمَّ صَلَّى فَصَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم ثُمَّ صَلَّى فَصَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم ثُمَّ صَلَّى فَصَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم ثُمَّ صَلَّى فَصَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم ثُمَّ قَالَ ‏ "‏ بِهَذَا أُمِرْتُ ‏"‏‏.‏ فَقَالَ عُمَرُ لِعُرْوَةَ اعْلَمْ مَا تُحَدِّثُ أَوَإِنَّ جِبْرِيلَ هُوَ أَقَامَ لِرَسُولِ اللَّهِ صلى الله عليه وسلم وَقْتَ الصَّلاَةِ‏.‏ قَالَ عُرْوَةُ كَذَلِكَ كَانَ بَشِيرُ بْنُ أَبِي مَسْعُودٍ يُحَدِّثُ عَنْ أَبِيهِ‏.‏ قَالَ عُرْوَةُ وَلَقَدْ حَدَّثَتْنِي عَائِشَةُ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يُصَلِّي الْعَصْرَ، وَالشَّمْسُ فِي حُجْرَتِهَا قَبْلَ أَنْ تَظْهَرَ‏.‏

Narrated Ibn Shihab:Once `Umar bin `Abdul `Aziz delayed the prayer and `Urwa bin Az-Zubair went to him and said, "Once in 'Iraq, Al-Mughira bin Shu`ba delayed his prayers and Abi Mas`ud Al-Ansari went to him and said, 'O Mughira! What is this? Don't you know that once Gabriel came and offered the prayer (Fajr prayer) and Allah's Messenger (ﷺ) prayed too, then he prayed again (Zuhr prayer) and so did Allah's Apostle and again he prayed (`Asr prayers and Allah's Messenger (ﷺ) did the same; again he prayed (Maghrib-prayer) and so did Allah's Messenger (ﷺ) and again prayed (`Isha prayer) and so did Allah's Apostle and (Gabriel) said, 'I was ordered to do so (to demonstrate the prayers prescribed to you)?'" `Umar (bin `Abdul `Aziz) said to `Urwa, "Be sure of what you Say. Did Gabriel lead Allah's Messenger (ﷺ) at the stated times of the prayers?" `Urwa replied, "Bashir bin Abi Mas`ud narrated like this on the authority of his father." `Urwa added, "Aisha told me that Allah's Messenger (ﷺ) used to pray `Asr prayer when the sunshine was still inside her residence (during the early time of `Asr)

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا عَبَّادٌ ـ هُوَ ابْنُ عَبَّادٍ ـ عَنْ أَبِي جَمْرَةَ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَدِمَ وَفْدُ عَبْدِ الْقَيْسِ عَلَى رَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالُوا إِنَّا مِنْ هَذَا الْحَىِّ مِنْ رَبِيعَةَ، وَلَسْنَا نَصِلُ إِلَيْكَ إِلاَّ فِي الشَّهْرِ الْحَرَامِ، فَمُرْنَا بِشَىْءٍ نَأْخُذْهُ عَنْكَ، وَنَدْعُو إِلَيْهِ مَنْ وَرَاءَنَا‏.‏ فَقَالَ ‏ "‏ آمُرُكُمْ بِأَرْبَعٍ، وَأَنْهَاكُمْ عَنْ أَرْبَعٍ الإِيمَانِ بِاللَّهِ ـ ثُمَّ فَسَّرَهَا لَهُمْ شَهَادَةُ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ، وَأَنِّي رَسُولُ اللَّهِ، وَإِقَامُ الصَّلاَةِ، وَإِيتَاءُ الزَّكَاةِ، وَأَنْ تُؤَدُّوا إِلَىَّ خُمُسَ مَا غَنِمْتُمْ، وَأَنْهَى عَنِ الدُّبَّاءِ وَالْحَنْتَمِ وَالْمُقَيَّرِ وَالنَّقِيرِ ‏"‏‏.‏

Narrated Ibn `Abbas:"Once a delegation of `Abdul Qais came to Allah's Messenger (ﷺ) and said, "We belong to such and such branch of the tribe of Rabi'ah and we can only come to you in the sacred months. Order us to do something good so that we may take it from you and also invite to it those whom we have left behind (at home)." So he said, "I order you to do four things and forbid you from four things: To believe in Allah" - and then he explained it to them "to testify that none has the right to be worshipped but Allah and that I am Allah's Messenger (ﷺ), to establish the prayers (at the stated times), to pay the Zakat (obligatory charity), to hand me the Khumus (fifth) if you acquire spoils of war. And I forbid from (using) Dubba, Hantam, Muqaiyyar, and Naqir (all these were utensils used for the preparation of alcoholic drinks)

أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا اللَّيْثُ بْنُ سَعْدٍ، عَنِ ابْنِ شِهَابٍ، أَنَّ عُمَرَ بْنَ عَبْدِ الْعَزِيزِ، أَخَّرَ الْعَصْرَ شَيْئًا فَقَالَ لَهُ عُرْوَةُ أَمَا إِنَّ جِبْرِيلَ عَلَيْهِ السَّلاَمُ قَدْ نَزَلَ فَصَلَّى أَمَامَ رَسُولِ اللَّهِ صلى الله عليه وسلم ‏.‏ فَقَالَ عُمَرُ اعْلَمْ مَا تَقُولُ يَا عُرْوَةُ ‏.‏ فَقَالَ سَمِعْتُ بَشِيرَ بْنَ أَبِي مَسْعُودٍ يَقُولُ سَمِعْتُ أَبَا مَسْعُودٍ يَقُولُ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏ "‏ نَزَلَ جِبْرِيلُ فَأَمَّنِي فَصَلَّيْتُ مَعَهُ ثُمَّ صَلَّيْتُ مَعَهُ ثُمَّ صَلَّيْتُ مَعَهُ ثُمَّ صَلَّيْتُ مَعَهُ ثُمَّ صَلَّيْتُ مَعَهُ ‏"‏ ‏.‏ يَحْسُبُ بِأَصَابِعِهِ خَمْسَ صَلَوَاتٍ ‏.‏

It was narrated from Ibn Shihab that 'Umar bin 'Abdul-'Aziz delayed the 'Asr prayer a little. 'Urwah said to him:"Jibril came down and led the Messenger of Allah (ﷺ) in prayer." 'Umar said: "Watch what you are saying, O 'Urwah!" He said: "I heard Bashir bin Abi Mas'ud say: 'I heard Abu Mas'ud say: "I heard the Messenger of Allah (ﷺ) say: 'Jibril came down and led me in prayer, and I prayed with him, then I prayed with him, then I prayed with him, then I prayed with him, then I prayed with him - and he counted off five prayers on his fingers

أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ الأَعْلَى، قَالَ حَدَّثَنَا خَالِدٌ، قَالَ حَدَّثَنَا شُعْبَةُ، قَالَ حَدَّثَنَا سَيَّارُ بْنُ سَلاَمَةَ، قَالَ سَمِعْتُ أَبِي يَسْأَلُ أَبَا بَرْزَةَ، عَنْ صَلاَةِ، رَسُولِ اللَّهِ صلى الله عليه وسلم قُلْتُ أَنْتَ سَمِعْتَهُ قَالَ كَمَا أَسْمَعُكَ السَّاعَةَ فَقَالَ سَمِعْتُ أَبِي يَسْأَلُ عَنْ صَلاَةِ رَسُولِ اللَّهِ صلى الله عليه وسلم قَالَ كَانَ لاَ يُبَالِي بَعْضَ تَأْخِيرِهَا - يَعْنِي الْعِشَاءَ - إِلَى نِصْفِ اللَّيْلِ وَلاَ يُحِبُّ النَّوْمَ قَبْلَهَا وَلاَ الْحَدِيثَ بَعْدَهَا ‏.‏ قَالَ شُعْبَةُ ثُمَّ لَقِيتُهُ بَعْدُ فَسَأَلْتُهُ قَالَ كَانَ يُصَلِّي الظُّهْرَ حِينَ تَزُولُ الشَّمْسُ وَالْعَصْرَ يَذْهَبُ الرَّجُلُ إِلَى أَقْصَى الْمَدِينَةِ وَالشَّمْسُ حَيَّةٌ وَالْمَغْرِبَ لاَ أَدْرِي أَىَّ حِينٍ ذَكَرَ ثُمَّ لَقِيتُهُ بَعْدُ فَسَأَلْتُهُ فَقَالَ وَكَانَ يُصَلِّي الصُّبْحَ فَيَنْصَرِفُ الرَّجُلُ فَيَنْظُرُ إِلَى وَجْهِ جَلِيسِهِ الَّذِي يَعْرِفُهُ فَيَعْرِفُهُ ‏.‏ قَالَ وَكَانَ يَقْرَأُ فِيهَا بِالسِّتِّينَ إِلَى الْمِائَةِ ‏.‏

Shu'bah said:"Sayyar bin Salamah, narrated to us, he said: 'I heard my father ask Abu Barzah about the prayer of the Messenger of Allah (ﷺ).' I said: 'Did you really hear him?' He said: 'As I can hear you now.' He said: 'I heard my father ask about the prayer of the Messenger of Allah (ﷺ).' He said: 'He would not mind if he delayed it - meaning 'Isha' until midnight, and he did not like to sleep before it or speak after it.'" Shu'bah said: "Then I met him later on and asked him. He said: 'He used to pray Zauhr when the sun had passed its zenith, and (he would pray) 'Asr and a man could walk to the farthest point in Al-Madinah and the sun would still be clear and hot. And Maghrib, I do not know the time he mentioned.' After that I met him and asked him, and he said: 'He used to pray Fajr then after the prayer a man could regarding it, sitting next to him, look at the face of someone he knew and he could recognize it.' He said: 'And he used to recite in it between sixty and one hundred (verses)

وعبادته التي هو مشغول بها لا ينتقل إلى غيرها ولا يفتر عنها لا يستكبرون عن عبادته ولا يستحسرون يسبحون الليل والنهار لا يفترون ومفتاح مزيد الدرجات هي الصلوات

وينبغي أن لا ينفصل من طرف عرفة إلا بعد الغروب ليجمع في عرفة بين الليل والنهار وإن أمكنه الوقوف يوم الثامن ساعة عند إمكان الغلط في الهلال فهو الحزم وبه الأمن من الفوات

الباب الأول في فضيلة الأوراد وترتيبها في الليل والنهار

يشير إلى أنه غير متطلع إلى الأوقات بل هو مع الذي يقدر الليل والنهار

فهذا سؤال جاهل ظالم ضال مفرط في الجهل والظلم والضلال لأن خلق الأضداد والمتقابلات هو من كمال الربوبية كالليل والنهار والحر والبرد واللذة والألم والخير والشر والنعيم والجحيم

خلفة لمن أراد أن يذكر أو أراد شكورا} [الفرقان: 62]، أي يخلف أحدهما الآخر ليتدارك في أحدهما ما فات في الآخر. ### $ 2 - بيان عدد أوراد الليل والنهار وترتيبها

Diagnosis of circadian rhythm sleep disorders.: Insomnia and excessive sleepiness are common in the investigation of sleep-disordered breathing. Circadian rhythm sleep disorders are perhaps the most often overlooked conditions in the differential diagnosis of these symptoms. Circadian rhythm sleep disorders manifest as misalignment between the sleep period and the physical/social 24-h environmental cycle. The two most prevalent circadian rhythm sleep disorders are delayed sleep phase (common in adolescents) and advanced sleep phase (common in

Intrinsic circadian period of sighted patients with circadian rhythm sleep disorder, free-running type.: Background: Circadian rhythm sleep disorder, free-running type (FRT), is an intractable sleep disorder in which sleep and wake times progressively delay each day even in normal living environments. This disorder severely affects the social functioning of patients because of periodic nighttime insomnia, excessive daytime sleepiness, and a high rate of comorbid psychiatric disorders. Although abnormal regulation of the biological clock is suspected, the pathophysiology of FRT has yet to be elucida

Identification of a Preliminary Plasma Metabolome-based Biomarker for Circadian Phase in Humans.: Measuring individual circadian phase is important to diagnose and treat circadian rhythm sleep-wake disorders and circadian misalignment, inform chronotherapy, and advance circadian science. Initial findings using blood transcriptomics to predict the circadian phase marker dim-light melatonin onset (DLMO) show promise. Alternatively, there are limited attempts using metabolomics to predict DLMO and no known omics-based biomarkers predict dim-light melatonin offset (DLMOff). We analyzed the human

Home dim light melatonin onsets with measures of compliance in delayed sleep phase disorder.: The dim light melatonin onset (DLMO) assists with the diagnosis and treatment of circadian rhythm sleep disorders. Home DLMOs are attractive for cost savings and convenience, but can be confounded by home lighting and sample timing errors. We developed a home saliva collection kit with objective measures of light exposure and sample timing. We report on our first test of the kit in a clinical population. Thirty-two participants with delayed sleep phase disorder (DSPD; 17 women, aged 18-52 years)

A randomized controlled trial with bright light and melatonin for the treatment of delayed sleep phase disorder: effects on subjective and objective sleepiness and cognitive function.: Delayed sleep phase disorder (DSPD) is a circadian rhythm sleep disorder. Patients with DSPD have problems initiating sleep if they go to bed at a conventional time, and they often have problems waking at desired times. If they rise early in the morning, they usually experience severe sleepiness during morning hours. In the present study, we investigated the short- and long-term effects on measures of subjective and objective sleepiness and cognitive function of bright light and melatonin treatm

Light-induced changes of the circadian clock of humans: increasing duration is more effective than increasing light intensity.: Study objectives: To evaluate the effect of increasing the intensity and/or duration of exposure on light-induced changes in the timing of the circadian clock of humans. Design: Multifactorial randomized controlled trial, between and within subject design Setting: General Clinical Research Center (GCRC) of an academic medical center Participants: 56 healthy young subjects (20-40 years of age) Interventions: Research subjects were admitted for 2 independent stays of 4 nights/3 days for treatment

Metabolic Effects of Intermittent Fasting.

The objective of this review is to provide an overview of intermittent fasting regimens, summarize the evidence on the health benefits of intermittent fasting, and discuss physiological mechanisms by which intermittent fasting might lead to improved health outcomes. A MEDLINE search was performed using PubMed and the terms "intermittent fasting," "fasting," "time-restricted feeding," and "food timing." Modified fasting regimens appear to promote weight loss and may improve metabolic health. Several lines of evidence also support the hypothesis that eating patterns that reduce or eliminate nighttime eating and prolong nightly fasting intervals may result in sustained improvements in human health. Intermittent fasting regimens are hypothesized to influence metabolic regulation via effects on (a) circadian biology, (b) the gut microbiome, and (c) modifiable lifestyle behaviors, such as slee…

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Implications of Circadian Rhythm in Dopamine and Mood Regulation.

Mammalian physiology and behavior are regulated by an internal time-keeping system, referred to as circadian rhythm. The circadian timing system has a hierarchical organization composed of the master clock in the suprachiasmatic nucleus (SCN) and local clocks in extra-SCN brain regions and peripheral organs. The circadian clock molecular mechanism involves a network of transcription-translation feedback loops. In addition to the clinical association between circadian rhythm disruption and mood disorders, recent studies have suggested a molecular link between mood regulation and circadian rhythm. Specifically, genetic deletion of the circadian nuclear receptor Rev-erbα induces mania-like behavior caused by increased midbrain dopaminergic (DAergic) tone at dusk. The association between circadian rhythm and emotion-related behaviors can be applied to pathological conditions, including neuro…

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Effects of isolation and confinement on humans-implications for manned space explorations.

Human psychology and physiology are significantly altered by isolation and confinement. In light of planned exploration class interplanetary missions, the related adverse effects on the human body need to be explored and defined as they have a large impact on a mission's success. Terrestrial space analogs offer an excellent controlled environment to study some of these stressors during a space mission in isolation without the complex environment of the International Space Station. Participants subjected to these space analog conditions can encounter typical symptoms ranging from neurocognitive changes, fatigue, misaligned circadian rhythm, sleep disorders, altered stress hormone levels, and immune modulatory changes. This review focuses on both the psychological and the physiological responses observed in participants of long-duration spaceflight analog studies, such as Mars500 or Antarc…

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A review of evidence for the link between sleep duration and hypertension.

There are lines of evidence from experimental sleep deprivation studies, population-based epidemiological studies, and an interventional study that point to the potential efficacy of adequate quality sleep to prevent and treat hypertension. Experimental sleep restriction has been shown to raise blood pressure and heart rate. Insufficient sleep on a chronic basis can raise average 24-hour blood pressure and lead to structural adaptations that entrain the cardiovascular system to operate at an elevated blood pressure equilibrium and increase the risk for hypertension. Disruptions in the timing and duration of sleep could also disrupt circadian rhythmicity and autonomic balance, which can increase the prevalence of the nondipping pattern, disturb diurnal rhythm of cardiac output, and increase blood pressure variability. Short sleep duration has been found to be associated with higher blood …

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Effects of optimal timed automatic awakening from a short daytime nap on cognitive performance, alertness, and fatigue.

Daytime napping improves performance, which is maximized with a post-N2 9-min nap. We evaluated whether a system that enables optimal-time automatic awakening using blood flow parameters could improve performance, sleepiness, and fatigue compared to no-nap. Additionally, we investigated whether its performance was comparable to manual awakening based on polysomnography. Eighty-one healthy adults (33.6 ± 12.8 years) were randomly assigned to automatic- or manual-awakening or rest groups. A task bout comprising a digit-symbol substitution test (DSST), visual detection test, and sleepiness and fatigue questionnaires was performed three times per session before napping and for six sessions after napping. In all post-nap sessions, sleepiness and fatigue in the automatic awakening group decreased, compared to the rest group, and were comparable to those in the manual awakening group. The DSST …

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Night shifts in interns: Effects of daytime napping on autonomic activity and cognitive function.

Objective: Night shifts have adverse cognitive outcomes that might be attenuated by daytime napping. The neurovisceral integration model suggests that resting vagally mediated heart rate variability (vmHRV) is linked with cognitive function. This study investigated the relationship between resting vmHRV and cognitive function after different nap durations in interns after shift work. Methods: A total of 105 interns were randomly allocated to one of three groups (non-nap, n = 35; 15-min nap, n = 35; 45-min nap, n = 35) to perform cognitive tests and resting vmHRV at 12:00, 15:00 and 18:00. Information processing (digit symbol substitution test; DSST), motor speed (finger tapping test; FTT), response selection (choice reaction time; CRT), and attention shifts (shifting attention test; SAT) were assessed. Resting vmHRV was assessed at baseline and during each cognitive task across groups. R…

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Rise and shine: A treatment experiment testing a morning routine to decrease subjective sleep inertia in insomnia and bipolar disorder.

Sleep inertia involves decreased performance or disorientation upon waking that lasts several hours and impairs functioning. Though sleep inertia is common in insomnia and may interfere with treatment, Cognitive Behavioral Therapy for Insomnia (CBTI) does not routinely include a component to address sleep inertia. The present study evaluates such a component, the RISE-UP routine, in CBTI for insomnia comorbid with bipolar disorder. We hypothesized that the RISE-UP routine would increase physical activity in the morning and reduce the duration and severity of self-reported sleep inertia. Sleep and sleep inertia were monitored in the week prior to and following the intervention with daily sleep diaries, actigraphy, and ecological momentary assessment (EMA). Participants were randomized to a bipolar-specific modification of CBT-I (CBTI-BP) with RISE-UP (N = 20) or a psychoeducation (PE) com…

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Better than sham? A double-blind placebo-controlled neurofeedback study in primary insomnia.

See Thibault et al. (doi:10.1093/awx033) for a scientific commentary on this article. Neurofeedback training builds upon the simple concept of instrumental conditioning, i.e. behaviour that is rewarded is more likely to reoccur, an effect Thorndike referred to as the 'law of effect'. In the case of neurofeedback, information about specific electroencephalographic activity is fed back to the participant who is rewarded whenever the desired electroencephalography pattern is generated. If some kind of hyperarousal needs to be addressed, the neurofeedback community considers sensorimotor rhythm neurofeedback as the gold standard. Earlier treatment approaches using sensorimotor-rhythm neurofeedback indicated that training to increase 12-15 Hz sensorimotor rhythm over the sensorimotor cortex during wakefulness could reduce attention-deficit/hyperactivity disorder and epilepsy symptoms and even…

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The effects of a mid-day nap on the neurocognitive performance of first-year medical residents: a controlled interventional pilot study.

Purpose: Despite shorter duty hours, fatigue remains a problem among medical residents. The authors tested the effect of a short, mid-day nap on the cognitive functioning and alertness of first-year internal medicine (IM) residents during normal duty hours. Method: This was a controlled, interventional study performed between July 2008 and April 2010. The authors recruited a nap group of 18 residents and a rest (control) group of 11 residents. Investigators connected all participants to an ambulatory sleep monitor before the beginning of their shifts in order to monitor rolling eye movements, a proxy for attention failures. At mid-day, both groups took Conner's Continuous Performance Test (CPT II) to evaluate their cognitive functioning and then were placed in a reclining chair designed for napping. The authors instructed nap group residents to nap for up to 20 minutes and chatted with c…

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A randomised controlled trial of cognitive-behaviour therapy for behavioural insomnia of childhood in school-aged children.

Chronic sleep problems can lead to the development of Behavioural Insomnia of Childhood - a sleep disorder involving problematic sleep-onset associations (i.e., parental presence), and resulting in impairments for children and family members. The aim of the present paper was to perform a controlled evaluation of cognitive-behaviour therapy (CBT) for Behavioural Insomnia. 42 children (M = 9.3 ± 1.9 yrs, range 7-13 yrs, 18f, 24 m) were randomised to CBT (N = 21) or waitlist control (N = 21). CBT consisted of 6 sessions, and combined behavioural sleep medicine techniques (e.g., sleep restriction) with anxiety treatment techniques (e.g., cognitive restructuring). Compared to waitlist controls, children receiving CBT showed significant improvements in sleep latency, wake after sleep onset, and sleep efficiency (all p ≤ .003), but not total sleep time (p > .05). CBT was also associated with a …

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Circadian rhythm disruption and mental health.

Circadian rhythms are internal manifestations of the solar day that permit adaptations to predictable environmental temporal changes. These ~24-h rhythms are controlled by molecular clockworks within the brain that are reset daily to precisely 24 h by exposure to the light-dark cycle. Information from the master clock in the mammalian hypothalamus conveys temporal information to the entire body via humoral and neural communication. A bidirectional relationship exists between mood disorders and circadian rhythms. Mood disorders are often associated with disrupted circadian clock-controlled responses, such as sleep and cortisol secretion, whereas disruption of circadian rhythms via jet lag, night-shift work, or exposure to artificial light at night, can precipitate or exacerbate affective symptoms in susceptible individuals. Evidence suggests strong associations between circadian rhythms a…

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Circadian clocks and insulin resistance.

Insulin resistance is a main determinant in the development of type 2 diabetes mellitus and a major cause of morbidity and mortality. The circadian timing system consists of a central brain clock in the hypothalamic suprachiasmatic nucleus and various peripheral tissue clocks. The circadian timing system is responsible for the coordination of many daily processes, including the daily rhythm in human glucose metabolism. The central clock regulates food intake, energy expenditure and whole-body insulin sensitivity, and these actions are further fine-tuned by local peripheral clocks. For instance, the peripheral clock in the gut regulates glucose absorption, peripheral clocks in muscle, adipose tissue and liver regulate local insulin sensitivity, and the peripheral clock in the pancreas regulates insulin secretion. Misalignment between different components of the circadian timing system and…

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The circadian clock and liver function in health and disease.

Each day, all organisms are subjected to changes in light intensity because of the Earth's rotation around its own axis. To anticipate this geo-physical variability, and to appropriately respond biochemically, most species, including mammals, have evolved an approximate 24-hour endogenous timing mechanism known as the circadian clock (CC). The 'clock' is self-sustained, cell autonomous and present in every cell type. At the core of the clock resides the CC-oscillator, an exquisitely crafted transcriptional-translational feedback system. Remarkably, components of the CC-oscillator not only maintain daily rhythmicity of their own synthesis, but also generate temporal variability in the expression levels of numerous target genes through transcriptional, post-transcriptional and post-translational mechanisms, thus, ensuring proper chronological coordination in the functioning of cells, tissu…

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Circadian rhythms and exercise - re-setting the clock in metabolic disease.

Perturbed diurnal rhythms are becoming increasingly evident as deleterious events in the pathology of metabolic diseases. Exercise is well characterized as a crucial intervention in the prevention and treatment of individuals with metabolic diseases. Little is known, however, regarding optimizing the timing of exercise bouts in order to maximize their health benefits. Furthermore, exercise is a potent modulator of skeletal muscle metabolism, and it is clear that skeletal muscle has a strong circadian profile. In humans, mitochondrial function peaks in the late afternoon, and the circadian clock might be inherently impaired in myotubes from patients with metabolic disease. Timing exercise bouts to coordinate with an individual's circadian rhythms might be an efficacious strategy to optimize the health benefits of exercise. The role of exercise as a Zeitgeber can also be used as a tool in …

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Circadian rhythms, nutrition and implications for longevity in urban environments.

Presently, about 12% of the population is 65 years or older and by the year 2030 that figure is expected to reach 21%. In order to promote the well-being of the elderly and to reduce the costs associated with health care demands, increased longevity should be accompanied by ageing attenuation. Energy restriction, which limits the amount of energy consumed to 60-70% of the daily intake, and intermittent fasting, which allows the food to be available ad libitum every other day, extend the life span of mammals and prevent or delay the onset of major age-related diseases, such as cancer, diabetes and cataracts. Recently, we have shown that well-being can be achieved by resetting of the circadian clock and induction of robust catabolic circadian rhythms via timed feeding. In addition, the clock mechanism regulates metabolism and major metabolic proteins are key factors in the core clock mecha…

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The importance of the circadian system & sleep for bone health.

Adequate sleep timed appropriately during the circadian night is important for numerous biological processes and systems. New evidence suggests that both sleep timing and duration may be important for optimal bone health as well. This review examines the diurnal variation of bone turnover markers (BTMs) and the importance of circadian clock genes in regulating bone mass. In addition, this review explores the evidence for a link between shift work (and its associated disturbances in sleep duration/quality and circadian alignment) and alterations in bone metabolism and bone health. Finally, we review how commonly used medications and over-the-counter substances (e.g. caffeine, melatonin) complicate the relationship between sleep and circadian disorders and bone health.

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Mutual influence of sleep and circadian clocks on physiology and cognition.

The 24-h sleep-wake cycle is one of the most prominent outputs of the circadian clock system. At the same time, changes in sleep-wake behavior feedback on behavioral and physiological circadian rhythms, thus altering the coordination of the body's clock network. Sleep and circadian rhythm disruption have similar physiological endpoints including metabolic, cognitive, and immunologic impairments. This raises the question to which extent these phenomena are causally linked. In this review, we summarize different physiologic outcomes of sleep deprivation and mistimed sleep and discuss the experimental evidence for a mediating role of the circadian clock machinery in this context.

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Health consequences of electric lighting practices in the modern world: A report on the National Toxicology Program's workshop on shift work at night, artificial light at night, and circadian disruption.

The invention of electric light has facilitated a society in which people work, sleep, eat, and play at all hours of the 24-hour day. Although electric light clearly has benefited humankind, exposures to electric light, especially light at night (LAN), may disrupt sleep and biological processes controlled by endogenous circadian clocks, potentially resulting in adverse health outcomes. Many of the studies evaluating adverse health effects have been conducted among night- and rotating-shift workers, because this scenario gives rise to significant exposure to LAN. Because of the complexity of this topic, the National Toxicology Program convened an expert panel at a public workshop entitled "Shift Work at Night, Artificial Light at Night, and Circadian Disruption" to obtain input on conducting literature-based health hazard assessments and to identify data gaps and research needs. The Panel…

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The Circadian System: A Regulatory Feedback Network of Periphery and Brain.

Circadian rhythms are generated by the autonomous circadian clock, the suprachiasmatic nucleus (SCN), and clock genes that are present in all tissues. The SCN times these peripheral clocks, as well as behavioral and physiological processes. Recent studies show that frequent violations of conditions set by our biological clock, such as shift work, jet lag, sleep deprivation, or simply eating at the wrong time of the day, may have deleterious effects on health. This infringement, also known as circadian desynchronization, is associated with chronic diseases like diabetes, hypertension, cancer, and psychiatric disorders. In this review, we will evaluate evidence that these diseases stem from the need of the SCN for peripheral feedback to fine-tune its output and adjust physiological processes to the requirements of the moment. This feedback can vary from neuronal or hormonal signals from th…

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Circadian Rhythm Sleep-Wake Disorders.

The circadian system regulates the timing and expression of nearly all biological processes, most notably, the sleep-wake cycle, and disruption of this system can result in adverse effects on both physical and mental health. The circadian rhythm sleep-wake disorders (CRSWDs) consist of 5 disorders that are due primarily to pathology of the circadian clock or to a misalignment of the timing of the endogenous circadian rhythm with the environment. This article outlines the nature of these disorders, the association of many of these disorders with psychiatric illness, and available treatment options.

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Circadian Clocks in the Immune System.

The immune system is a complex set of physiological mechanisms whose general aim is to defend the organism against non-self-bodies, such as pathogens (bacteria, viruses, parasites), as well as cancer cells. Circadian rhythms are endogenous 24-h variations found in virtually all physiological processes. These circadian rhythms are generated by circadian clocks, located in most cell types, including cells of the immune system. This review presents an overview of the clocks in the immune system and of the circadian regulation of the function of immune cells. Most immune cells express circadian clock genes and present a wide array of genes expressed with a 24-h rhythm. This has profound impacts on cellular functions, including a daily rhythm in the synthesis and release of cytokines, chemokines and cytolytic factors, the daily gating of the response occurring through pattern recognition rece…

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Circadian pacemaking in cells and circuits of the suprachiasmatic nucleus.

The suprachiasmatic nucleus (SCN) of the hypothalamus is the principal circadian pacemaker of the brain. It co-ordinates the daily rhythms of sleep and wakefulness, as well as physiology and behaviour, that set the tempo to our lives. Disturbance of this daily pattern, most acutely with jet-lag but more insidiously with rotational shift-work, can have severely deleterious effects for mental function and long-term health. The present review considers recent developments in our understanding of the properties of the SCN that make it a robust circadian time-keeper. It first focuses on the intracellular transcriptional/ translational feedback loops (TTFL) that constitute the cellular clockwork of the SCN neurone. Daily timing by these loops pivots around the negative regulation of the Period (Per) and Cryptochrome (Cry) genes by their protein products. The period of the circadian cycle is se…

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Pathophysiology and pathogenesis of circadian rhythm sleep disorders.

Metabolic, physiological and behavioral processes exhibit 24-hour rhythms in most organisms, including humans. These rhythms are driven by a system of self-sustained clocks and are entrained by environmental cues such as light-dark cycles as well as food intake. In mammals, the circadian clock system is hierarchically organized such that the master clock in the suprachiasmatic nuclei of the hypothalamus integrates environmental information and synchronizes the phase of oscillators in peripheral tissues. The transcription and translation feedback loops of multiple clock genes are involved in the molecular mechanism of the circadian system. Disturbed circadian rhythms are known to be closely related to many diseases, including sleep disorders. Advanced sleep phase type, delayed sleep phase type and nonentrained type of circadian rhythm sleep disorders (CRSDs) are thought to result from dis…

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Circadian rhythm sleep disorders and phototherapy.

Circadian rhythm sleep disorders are characterized by a desynchronization between the timing of the intrinsic circadian clock and the extrinsic light-dark and social/activity cycles resulting in symptoms of excessive sleepiness and insomnia. This article explores the six recognized circadian rhythm sleep disorders: delayed sleep phase syndrome, advanced sleep phase syndrome, non-24-hour sleep-wake syndrome, irregular sleep-wake pattern, shift work sleep syndrome, and time zone change syndrome. Additionally discussed are the therapeutic roles of synchronizing agents, such as light and melatonin.

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The effects of sleep extension and sleep hygiene advice on sleep and depressive symptoms in adolescents: a randomized controlled trial.

Objective: Sleep problems are common and persistent during adolescence and can have negative effects on adolescents' mood. To date, studies that investigate the effects of sleep extension on adolescents' sleep and depressive symptoms are still lacking. This study aims to investigate the effects of gradual sleep extension combined with sleep hygiene advice in adolescents with chronic sleep reduction on objectively measured sleep, self-reported sleep problems and depressive symptoms. Methods: Fifty-five adolescents with chronic sleep reduction (mean age: 15.44 years; 85.5% females) were included in the study. Participants were randomly assigned to either a sleep extension group (gradual sleep extension by advancing bedtimes in the evening and receiving sleep hygiene advice) or to a control group (no instruction). Sleep was measured with actigraphy during three weeks, the first week was the…

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