Biphasic Sleep - Cycle Question

[flaime]

Ok recently i have been trying to switch to a biphasic sleep schedule where i sleep at 5-6.30 and then at about 2-6.30

I have been having troubles with keeping to the schedule due to being out on day trips and other events which mean i miss my nap, however i find that on the days i miss the nap i can just have a normal nights sleep and be fine. In fact i missed the nap yesterday, went to bed at 2 and woke up exactly 6 hours later which was great.

But anyway i had a question.

The other morning i went to sleep having missed the nap and decided to have a lie in. I woke at around 9 and lay in bed. I looked at my clock and took note of the time and decided to have one more "90 minute sleep cycle"

I went to sleep and have a very vivid dream and when i woke i thought it must have been 90 minutes - as the REM part of the sleep takes place at the end of the sleep cycle.

However much to my surprise i saw that only about 55 minutes had gone since i looked at the clock.

I was wondering if it is possible to have a complete sleep cycle in around 60 minutes? Normally mine are the usual 90 minutes but on this occasion it appears to have been only 60 minutes long!

Any thoughts would be appreciated

[Calculusaurus]

The 90-minute cycle is actually a "textbook example" that loses all applicability in real-world situations.

It's a bit of a false meme that's spread like wildfire across sleep advice websites.



The top graph is the "textbook example" I'm refering to. And those aren't even 90m cycles. Cycle length changes depending on our circadian phase (i.e. time of day). Notice how cycles in the early part of sleep are much longer than 90m.

As we age, our sleep architecture becomes much more choppy.

And it's not just age, your homeostatic and circadian sleep drives will turn those cycles into anywhere from 60m to 120m...

Take a sip of alcohol or caffeine before bed and your sleep stage architecture will become sporadic - no more 90m cycles. Too much stress (i.e. cortisol)? No more cycles.

Worse, you're doing polyphasic sleep. You'll almost never see consistent cycles. You're sleeping against your natural circadian drive. Your sleep architecture is going to be very different. The 90m rule will have no application for you.

Right now I'm looking at real data of sleep stage architecture graphs from a pdf version of Stampi's Why We Nap book. The data is from polyphasic subjects. I can't see any evidence of predictable cyclic patterns.