What would mean a doctor rather than a course

These are in lesson one and not buried at the end, because someone tired enough may never reach lesson six.

One is urgent. If you have fallen asleep, or nearly fallen asleep, while driving, that goes to a doctor this week and you should not drive drowsy in the meantime.

Then the rest. You snore, or somebody has seen you stop breathing in your sleep, or you wake with a headache or a very dry mouth, or you are sleepy all day despite spending enough time in bed. You get unpleasant sensations in your legs in the evening with an urge to move them. You act out dreams, or walk, or shout in your sleep. Your sleep changed when a medication changed. You are using alcohol, or increasing doses of something, to get to sleep. Or there is low mood, loss of interest or hopelessness alongside it.

And the threshold that matters most: three nights a week or more, for three months or more. That is the point at which this has stopped being a rough patch.