If you fall asleep at 8pm and wake up at 4am with 8 hours of sleep why do you feel extremely tired by 10am, but if you go to sleep at 11pm and wake up at 7am you can stay up all day without feeling very sluggish? Does it have something to do with waking up while it’s still dark?

Question

If you fall asleep at 8pm and wake up at 4am with 8 hours of sleep why do you feel extremely tired by 10am, but if you go to sleep at 11pm and wake up at 7am you can stay up all day without feeling very sluggish? Does it have something to do with waking up while it’s still dark?

In: Biology

Answer 1

This is because there is usually no sunlight at 4am. At 7am, there is sunlight, so your internal clock can suppress melatonin production to go into lighter sleep and eventually wake up.