Probably Dance

I’m writing this at 2am, having already slept from 9pm to 1am. I will sleep again from 4am to 7am. This is apparently called “biphasic sleep”, which I first heard about in the 2022 article The forgotten medieval habit of ‘two sleeps’. I had read that article with interest, because this has happened to me occasionally over the years: I’d fall asleep early, then wake up to spend a few hours restless before finally falling back asleep in the early morning hours. After reading that this used to be normal, I finally decided to just let it happen when it does, which is about two or three times a week.

What really made it happen this commonly is having one year old twins. (almost two years actually, time flies…) After we put the kids to bed at 8pm, I’m often just exhausted. I lay down on the couch to rest a little and fall asleep within 20 minutes. I wake up again between 11pm and 1am. If it’s closer to 11pm I can go back to sleep and sleep through the night. If it’s closer to 1am, it’s impossible to fall asleep again. I’m wide awake.

On other nights I actually just rest for thirty minutes on the couch without falling asleep. I then spend the evening normally before falling asleep later, at 11pm or midnight.

In all cases I wake at 7am because that’s when the kids wake up. (yes, toddlers sleep from 8pm to 7am, plus a two hour nap in the middle of the day)

On “normal” nights my evenings are of uneven quality. Most evenings I’m tired and am not able to get anything done. I might just spend the evening reading or playing games, but I’m unable to program. On biphasic nights I’m wide awake and full of energy. It’s easy to be productive, doing programming, writing (this blog post), or even exercising. In fact it’s tempting to want to stay up too long. I have to force myself to go back to sleep, otherwise the next day is ruined.

On “normal” nights I don’t need an alarm to wake up at 7am. In fact I often wake up a little early, between 6am and 6:30am. On biphasic nights I need an alarm, but still wake up easily without feeling tired. (if I didn’t stretch the nightly wake time too long) I have been a morning person ever since I lived in an apartment with a south-east-facing bedroom where the sun often woke me at 5am. When I lived there I found that I enjoyed waking up early because the morning hours are often higher quality than the evening hours. After I moved from there I didn’t wake up that early any more, but I still woke up easily in the morning without feeling tired.

Now I find a similar quality that I had in the morning hours, except in the middle of the night. If I could choose between one of the two, I’d definitely choose sleeping fully through the night and having more time from 5am to 7am, but having the nighttime hours is also nice. Having two toddlers around means I don’t get much time to myself any more.

If you think this is for you, what do you have to do? Not much. When you feel tired in the evening, just have low lights and let yourself fall asleep. I recommend reading challenging texts or trying to solve challenging puzzles. I seem to fall asleep when I have to re-read a text multiple times or when I’m stuck on a puzzle for a while, looking for new angles. Then, when you wake up in the middle of the night and can’t go back to sleep, just get out of bed. Don’t toss and turn being unable to sleep. Just skip that phase. Then don’t stay up too long, because you do need more sleep in the morning.

What Helps or Hurts

Screens – I don’t think screen use affects whether I stay awake or not. I do make my screen as dark as possible in the evenings, but I also do that on evenings where I stay awake. On biphasic nights I’ll fall asleep equally easily whether I’m reading a book, on a phone, or on a computer.

Caffeine – This definitely affects biphasic sleep, but I’m not sure I have a clear conclusion yet. The main effect is that I have biphasic sleep less often on days when I have caffeine. But if I’m very tired, I might still fall asleep early and then caffeine instead stretches my nightly waking hours. E.g. recently I had very bad (normal) sleep the previous night, and drank matcha to make it through the day. Since I was so tired I still fell asleep before 9pm, but then I was unable to fall asleep at night again, so my second sleep was only from 6am to 7am, which is not enough.

Physical activity – This can definitely keep me awake. If something needs to get done in the evening, even if I’m tired, I won’t have biphasic sleep. But on nights where I fall asleep at 9pm, I’m often not able to do much around the house. The couch has a very strong pull.

Naps – They kill biphasic sleep. On weekends I often nap when the kids are napping. On those days it’s easy to stay up until 11pm. I don’t have that option when I have to work during the week.

The main thing that’s required is the right mindset. I used to fight falling asleep early because I thought it ruined my sleep for the night. I would worry about waking up at odd hours and not getting enough sleep and being tired the next day. I’d think that it’s better to stay awake until 11pm and then sleep the full night than fall asleep early and wake up at night. Now that I know of biphasic sleep, and I have figured out how to have it without being more tired the next day, I just listen to my body when I get tired.

Finally, how do you go back to sleep when you’re wide awake in the middle of the night? I find that after 4am, even if I feel totally awake, all it takes is to lay down and wait. I’ll feel wide awake, unable to sleep, and then the next thing I know it’s 7am and I get woken by my alarm.