Here’s what I’ve learned:

  1. I always feel pretty good after a night with an unusually high amount of “deep sleep”.
  2. I fairly often feel great even when I don’t get very much deep sleep.
  3. Sometimes less sleep is totally fine.
  4. It takes getting significantly less than my normal sleep to feel bad after just one night of poor sleep. Normally, it will take 3-4 nights of low sleep to start having ill effects.
  5. Interrupted sleep has the most negative effect on how I feel in the morning, but is also nearly fully resolved by just staying it bed and getting an additional 2-3 hrs of deep sleep throughout the morning.
  6. Caffeine in the evening can cause me to stay awake later, but doesn’t have any discernable other impact on my sleep.
  7. Exercise helps me sleep well, but less than I thought.
  8. Anything over 6 hours and 45 minutes for me is absolutely fine. Anything over 7 hours and 15 minutes feels like “a lot”. I can sleep as little as 6 hours and 15 minutes with virtually no impact unless that goes on for days at a time.

I think the most important of these is (5)— if I find myself up at 2 AM, and again at 4 AM, I will do my best to send a few emails to say I’m having a rough night and make sure I can sleep from 7 to 10 or 10:30 AM whenever possible. This almost always ensures I won’t stack several days of bad sleep. If it’s not possible, I try and get a nap in around 4 or 5 PM that day.