[parkerhoyes]

Exactly. 24h 50m is the average I calculated after tracking my sleep for over a year. On average, the time that I wake up and go to sleep gets later by 50 minutes each day relative to a 24 hour day.

I'm currently waking up around 2am local time. In two weeks, I'll be waking up around noon.

If I lived on Mars, where the day length is 24h 37m, I would feel right at home (aside from the lack of breathable air).

[ehsanu1]

Could you please briefly explain the way you cam calculate your cycle based on average time sleeping? I have to get up using alarms at times that are not related to how my body is feeling about waking up, so I don't see how tracking that would help.

I tend to start sleep later and later until I reach some dynamic equilibrium between sleep deprivation due to fixed wake up times and the tendency to delay sleep onset.

[parkerhoyes]

I almost never use an alarm anymore - there's no need to, my body knows exactly when to wake up because of my circadian rhythms (that's the way humans were supposed to work after all - we didn't evolve to use alarm clocks). Of course, the time my body "knows" to wake up is almost an hour later than it should, and that's the whole problem.

The way I calculated the length of my circadian rhythm cycle wasn't by tracking the duration of my sleep, it was by tracking the exact time I naturally woke up every day. I then calculated the difference in the time I woke up each day (the daily "drift" in my sleep cycle). The median of those "drift" values turned out to be around 50 minutes, which means my sleep cycle is 24h 50m on average.

It might seem like not using an alarm clock would bias those measurements, but that's actually not the case. Even assuming the fact that I don't use an alarm clock makes me sleep in (it doesn't, but for the sake of argument), that would only effect the average time that I wake up every day, not the average drift in my sleep cycle. There are a number of other biases that would have to be accounted for if this was an actual study, but for my purposes that's accurate enough.

In reality, everybody has a different natural circadian rhythm cycle. If that cycle is close enough to 24h, then you'll have a "normal" sleep cycle. If it's long enough to cause insomnia / delayed sleep onset but your body can still "compensate" (that "compensation" mechanism is called entrainment in chronobiology), then that's called Delayed Sleep Phase Syndrome (I'm not a doctor, but that sounds like what you're describing). If your natural circadian rhythm cycle is so long that your body isn't capable of "compensating" to a 24h cycle, then that's called Non-24-Hour Sleep-Wake Disorder. Delayed Sleep Phase Syndrome is far more common than Non-24.

As for this point:

> I have to get up using alarms at times that are not related to how my body is feeling about waking up, so I don't see how tracking that would help.

I'm afraid tracking it didn't really help me at all - I simply tracked it because I was curious. My "solution" was simply to let my body do it's thing, but that's not an option for most people who have fixed work schedules or other commitments every day.

[ehsanu1]

Seeing this long later, but thank you for the detailed reply.