Really though, the math is pretty unsurprising isn't it? Optimum sleep time is usually considered 7 or 8 hours, we'll say 7.

If you sleep 4 hours a night for 5 nights, you wind up 15 hours short. Why would one expect to make up for that with 3 "extra" hours?

In my experience sleeping "extra" 1.5 hours in two night in row is much more helpful than sleeping 3 "extra" hours in one night.

Check out the Stanford Sleep Book to learn more about sleep debt: http://stanfordsleep.ning.com/

Warning: the above link autoplays audio.

Melatonin has really helped me regularize my sleep pattern and get better sleep quality. I recommend it. So far I've been taking 3 mg supplements, but I've read that this might be overkill, and plan on moving to 1 mg.

http://en.wikipedia.org/wiki/Melatonin

Melatonin works alright as long as you wind yourself down a half hour or so before you take it. I found that if I took it while still up late on the computer, I would get tired, but not enough to fall asleep.

Interesting... I just started a biphasic sleep schedule (4.5 hours of sleep from 1:00 to 5:30, and then 1.5 hours of sleep from 19:00 to 20:30) but now I'm wondering if the cost will outweigh the benefits.

I've done a 6 and 2 biphasic schedule (or sometimes 7 and 3), and I felt better than I ever had before. It's difficult to fit the nap in with work though.

I think in many ways the "Italian" sleep schedule (up at 7, awake till 2, sleep till 5, awake till 2) is very natural. It's no less sleep, but it feels more refreshing somehow.

Depending on where you live, the hottest hours of the day are usually between 12 - 5. Maybe it's instinctual for predators to not want to do stuff during those hours?

Biphasic sleep schedules are arguably the default setting for non-industral society humans - http://en.wikipedia.org/wiki/Segmented_sleep - and while it appears to have benefits in terms of mood and alertness, it may not be entirely healthy as a way to reduce the total amount of sleep if you need more.

Biphasic is fine, sleep deprivation is problematic. You've got a grand total of 6 hours, when most humans do best on 7-8, so you might be running a bit low.

Interestingly, this submission was perfectly timed for me. I slept 4 hours each on Sunday and Monday night, then I stayed up all night Tuesday night. Wednesday I slept 13 hours, and then last night I got tired around 10 pm and slept 10 more hours. Before seeing this submission, I thought it was a little weird to sleep so much two nights in a row.

Now I'm feeling truly refreshed, and I'm ready for another late-night weekend :)

It isn't self evident. That's why research and studies are performed.

We can assume or think a lot of things are self evident, but if there isn't any hard facts lying around, we can never be sure.

Ok, self-evident is the wrong word. Properly expressed, what they describe and conclude is exactly what I have experienced all my life. If I stay up all night, or close to all night, the following night I will sleep for 10+ hours. The following night after, another 10+ and the 3rd night 8-9. Not by choice, I just can't be woken by my alarms.

This pattern repeats almost without fail.