What causes the sleep-related “second wind,” where one can go 24 hours without sleep and be on the verge of collapse, then all of a sudden, for a few minutes or hours at least, hardly feel drowsy?
I have only heard of the term as related to exercise. After a period of exhaustion, one can suddenly discover renewed energy and continue on at a high pace. The cause seems to be replenishment of bodily resources, sort of a “catching up” of the flow of resources needed for exercise.
I’ve encountered CheeseDonkey’s example many times, in many situations. And I too am curious about it.
I have never heard “Second wind” used that way; I’ve always heard it as something that experienced athletes with lots of fitness* get; and I always assumed that it was caused by the body switching from anaerobic to aerobic burning, because suddenly, everything gets easier and it seems to occur after 30-45 min.
*established in previous training sessions over a long period
Perhaps it has to do with diurnal cycles. If you stay awake for 24 hours then by that time it’s morning and you should be naturally up anyway, whereas a couple hours before it was 5 am and your body was telling you you should be asleep at that time of day.
I’ve definitely experience what the OP described. And have always described it as a ‘second wind’ too.
I think this is correct. Sleep studies show that your brain wave patterns tend to follow a pattern parallel to what happens when you sleep even if you force yourself to stay awake, so your alertness flags during when you would normally be in deep sleep, and you have a “second wind” at the time you might normally wake up. I have pulled a few all-nighters and experience a second wind around the time the sun comes up. Exposure to light could possibly play a role as well.
There’s even a (very short) article about it in Wikipedia: Second wind (sleep)