At my wife's urging, I just read Why We Sleep, by Matthew Walker. It has already convinced me to change my habits. The short version is that we have all long known that inadequate sleep is bad for our health, makes us worse drivers and students, and that the ubiquity of electrical illumination may not be an unmixed blessing. The reality is worse. Those things are true, and more dramatically than we like to think; secondly, there are other things like higher blood pressure, lower testosterone and sperm count, worse glucose processing, worse memory, increased depression, mania, and anxiety, irritability, bad judgement and loss of temper; thirdly, many of the benefits of sleep occur in hours 6-8 and have to be set up by the previous 6 hours; fourthly, you can't recover much of what you lost from a bad night's sleep by getting more the next night or even over the next week. Each bit of damage is real, however slight, and unrecoverable.
So get eight hours every night. Getting used to being one of those awake-achievers who gets by on 5-6 a night (which you brag about), is a set-up for Alzheimer's.
Some background on how bad my own decisions have been, which is why I may seem harsh now: I have had a sleep movement disorder, twitching and even kicking, for decades. This makes the deepest sleep more elusive. I avoided a sleep specialist referral for years even though my snoring is horrendous, because I have hypopnea, not apnea. That is, my night breathing was poor, but never stopped in those non-breathing intervals that send spouses into panic. So I figured No Biggie. Though I knew I was by nature a night owl with a later clock, I kept jobs which required early arrivals. I even worked the graveyard shift for four years, because my wife and I were determined to reduce the number of hours our children spent in (gasp) day care overrode other considerations. Now that I think how one's children turn out is much, much more genetic than environmental, this looks like an amazingly bad choice. 22hrs/week versus 16 hrs/week in day care? That's a big deal?
My first sign of aging - okay, I started balding at 20, so my second sign of aging - was bags under my eyes. By longstanding folk wisdom, we get bags under our eyes because of lack of sleep, but I laughed that off as accidental. Well no, it actually is a sign of inadequate sleep, and it shows up as early as childhood. I attributed my inability to drop off to sleep at a decent hour (the few times I tried), always lying abed 60-90 minutes, as anxiety. That goes back as far as high school, and has to do with night owl/morning lark differences. Whenever I had days off with no morning obligations I would sleep 11 hours, days running, my body trying to catch up.
I did catch a 45 minute nap at lunch on work days because I was so impossibly sleepy, and as we are designed for biphasic sleep and should have kept that siesta pattern, I did stumble on one healthy thing. Here's the thing: I was not one of those awakeness-warriors determined to press on, I get 6.5-7.5 hours per 24 (including the nap). It's just that it wasn't very good sleep until about 10 years ago, and that's still not enough. I am a night owl with a half-hour commute for 8am. It just doesn't work. I ignored this, thinking it was bad, but not very bad.
The one that shook me awake, so to speak, was the glucose processing. 50% worse the next day on six hours sleep versus 8. I have greatly reduced my starches (sweets were never a thing) over the last 6-7 years, and have fair but not terrible eating habits, but did not start losing weight until my semi-retirement 15 months ago, at which point I started sleeping more. So I'm gonna ride that sleep solution hard and get even more sleep. It's those last 90 minutes that lay down the glucose and blood-pressure healing mechanisms (medical details in the book).
Sleep cures nothing but treats everything, it seems.
Discussion: Teenagers move into the night-owl category, then drift back as adults into the 40% morning lark, 30% night owl, 30% midrange continuum. A century ago high school started at 9am. We moved to earlier starts in the 20's and 30's, and it's not good. Some districts are developing options for later starts. The 20% of kids who remain early risers dominate at school, but the 80% get cheated. It's not laziness or lack of discipline (necessarily). Their bodies won't fall asleep earlier, and the "getting wiser as you get older" is more biology than decision.
There are a few employment categories which are worst about sleep, but medicine and the military are the worst. I get the reasoning. They are trying to raise the floor, of making adequate decisions automatic even under the worst of conditions, because sometimes the conditions are terrible. With the military, the camaraderie of working through hardship is also important. Yet this is in contrast to, say, athletes, who strive to find the ceiling, the best conjunction of diet, sleep, and training for optimal performance. That might be more important information in today's warfare and medical care.
Plus, why would want your army, or your basketball team, to have less testosterone?