Six!! That's crazy. An interesting tidbit I learned from the (awesome) book Why We Sleep was that a lot of people *think* that they can perform optimally on less than an optimal amount of sleep. They don't have the ability to realistically evaluate their performance at all.

And a personal reflection I want to add — it's even trickier when those people who fail to sleep adequately are above average intelligence. I've met quite a few such people, especially at work. Their argument is that they can do their work just fine — they compare themselves with people who are not as smart but get the proper amount of sleep.

Now, imagine if everyone who is gifted actually slept as much as they have to...