How sleep works: what pulls you to bed, and what your brain does all night
Staying up all night: which hour is the hardest, and why
Stay up all night, and the sunrise makes you feel better, not worse, though you have been awake longer. Which hour of an all-nighter is really the hardest?
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1
10 am. Strange: you feel better than at 5 am, and you have been awake five more hours. Even Rono, up again after his nap on the board, is laughing. Miva's guess was wrong.
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2
Two forces were at work all night. The sleep pressure only climbs while you stay awake. Your body clock pushes back with a wake signal that rises and falls with the day.
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3
How sleepy you feel is the gap between them. At 5 am, the wake signal was at its lowest: a huge gap. Since dawn, the signal has climbed faster than the pressure. Your second wind is the clock.
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4
The game ends at noon, and you have raised a lot of money. Rono goes straight home to bed. You hold on until your usual bedtime.
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5
At 10 pm you fall asleep in minutes, your jar of sleep pressure fuller than ever. By morning, it will be empty. What does your brain do all night to empty it?
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Quick check
A nurse ends a night shift at 8 am and goes to bed at 9, very tired. Why does she often wake up after only a few hours?
Show the answer
Her sleep pressure is high, but her body clock's wake signal climbs all morning and wakes her. Sleep in the daytime is often short for this reason.
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Go further
The two forces have names in the lab.