Before you say "I can function okay on 5 hours of sleep", have you seen/heard the AT&T commercial(s)?
Sleep is imperative. It isn't a waste of time, you don't get ahead by cutting out sleep, and you aren't winning hardcore points for "getting by" on sleeping less.
Most people who tell me they're fine with less sleep don't have a clue just how good they could function on 8 hours (or how bad they truly feel running on less).
So, how little is too little?
The National Sleep Foundation claims sleep deprivation is anything less than 7.5 hours a night and everything you lose adds up. If you sleep 5.5 hours a night over a week, you are going in sleep debt; to the tune of 14 hours a week, and that is a debt that will catch up to you. Luckily, there's no interest and you can repay it if you work at it.
Ok, who cares? Here's why sleep matters...
In a recent Harvard study, participants were intentionally sleep deprived (5.6 hours/night over the course of 3 weeks) with astounding results. Blood sugar levels went haywire, with some high enough to be prediabetic. Metabolism slowed-enough to estimate a 10 to 12 pound weight gain over the course of a year. So, for those of you who have committed to working out every day and eating healthy (whatever that means to you) but still aren't seeing physique results you want, maybe you need to up your zzz's at night.
Human Growth Hormone (GH), a substance which has been banned by nearly every sport due to the unfair advantage it provides athletes, is naturally produced by the human body. In men specifically, some studies show that nearly 70% of this happens during sleep. Are you constantly sore or dragging behind? Try an extra bit of sleep at night.
Problem solving and life:
There are a multitude of studies that show your brain's ability to create new connections and improve memory and learning during sleep. Keep forgetting where you put your keys? Have trouble learning new skills or computer tasks? Maybe you need a bit more sleep.
The bottom line is you are not GREAT if you're missing out on sleep. Being just OK isn't okay with us-and it shouldn't be okay with you either. No matter how much sleep you have neglected, you can correct your sleep debt by committing to a regular 7.5+ hour a night sleep schedule NOW!