Why does the sleep need not accumulate proportionately from previous days where we didn’t sleep enough?

Question

If you slept only 4 hours the previous day and you got a good night’s rest the next day, you don’t wake up 12 hours later but rather about 8-9.

In: Biology

Answer 1

I think your question is slightly flawed. You don’t wake up at a certain time because that’s all the sleep you needed, but instead you wake up due to a natural cycle within your body called the circadian rhythm.

Answer 2

You absolutely do accumulate fatigue if you do not sleep enough over a number of days. I can’t understand why you would not know this.

Answer 3

You’ll start to accumulate sleep debt. You may not feel it too much for missing one night of well rested sleep, but it will eventually start to add up and the effects of sleep deprivation will become more apparent.

Answer 4

In a nutshell, waking up (even without any loud noises causing that) doesn’t always equal not needing any additional sleep.