This week I finished reading “Internal Time: Chronotypes, Social Jet Lag, and Why You're So Tired,” which has been on my in-progress list for a while. I found the book itself somewhat hard to power through after a while due to the writing style, but the ideas in it addressed problems I often have with sleep.
Over the years, researchers have built an increasing body of evidence indicating that most animals are imbued with an internal timekeeping system. Such systems allow the animals that have them to take advantage of patterns in the environment which vary over time, such as the availability of food or the absence of predators. Humans also have one of these clocks, and it can have a strong effect on a person’s behavior.
There are many different kinds of clock behaviors, and the particular ones a given person has determine their “chronotype”. Generally chronotypes are grouped along two main axes: when do you sleep, and how long you sleep for. Early chronotypes will tend to go to sleep earlier and wake up earlier than others with the same duration; longer chronotypes will go to bed earlier and wake up later than others with the same mid-sleep time.
Of course, the clock is not fixed - we’re not machines. External stimuli influence the “calibration” of the internal clock, and understanding how these mechanisms work is important to understanding how to improve your sleep. Light in particular is a very strong signal, and intense light sources (such as the sun) have the greatest ability to shift the clock’s timing. When we stay up late in our homes looking at bright screens with bright lightbulbs, we send a signal to our bodies that the day is still progressing and that the internal day should shift towards midnight. Similarly, the low sun exposure we get during a day in the office does little to help move the clock back, and so we get a poorly-synchronized internal timepiece.
I’ve tried addressing this in my own life by buying LifX smart lightbulbs and programming them to shift towards the red side of the spectrum as the day goes on, and installing f.lux on my laptop to do the same there. This seems to help, but it’s not quite enough: I need to get more sun exposure in the morning.
The problem is, I tend to stay up too late regardless of how tired I am, and my systems for enforcing a workable bedtime just aren’t up to the job. Recently my sleep debt has started to catch up with me and cause trouble, so I’ll be looking at ways to structure my environment to help me do better on this.