How does circadian rhythm work? Is it more important than hours slept?


I’ve been dabbling with my own sleep cycle and trying to find out why I’m always waking up tired. I looked up a circadian rhythm calculator and based on my wake up time of 6am, I should be going to bed at certain times. I’m a night owl so I usually would go to bed around 1am, giving me 3 full sleep cycles.

I tried that last week and I woke up every day feeling pretty good overall, but I noticed when going to the gym or doing anything after work, I felt tired and disinterested due to lack of sleep.

So this week I decided to get extra sleep and see how I feel, but not within my circadian rhythm. I woke up this morning feeling the most tired I’ve been in a long time and that’s with nearly 2 hours extra of sleep.

So how does it work, and which is more important for feeling well rested if I had to choose only one? Within the rhythm or more hours slept?

In: 1

A consistent rythm matters… what is important is you give your body these clear signals of wakeup and sleep time at consistent ideally same times…ideally 8 hours + if you can get it but most can handle 6 well enough

Long story short you have cells in your eyes (melanopsin ganglion cells)

These measure light intensity. They are slightly angled upwards so they kinda scan the skyline funny enough…it is part why desk ergonomics have screens slightly above eyeline and why office skylights help with mood and alertness. If you dont feed these receptors with light you kinda get sleepy…they do dictate when we are alert almost…those also set your chronological clock pretty much… in many blind people lacking these you get insomnia because of this.

Anyway those need to be fed with light to get that it is a new morning.. usually in winter times and early wake times we do not get enough light in the morning to set this ryrhm… its its whole thing, what we call winter depression plays partially into it.

The later it is the more you want to get light from indirect sources.. so ideally more dim lights in order to not overstimulate these receptors.. this is typically what people say with blue light being bad. It is super disruptive in the evening phases….it is however all direct light. Blue light is just the most disruptive.

In order to fall asleep you need a temperature drop. Your limbs are good heat vents. So a slightly cooler room and limbs out of blanket makes u sleep faster.

We then reach a temperature minimum. Our brain gets a cortisol spike. After 2-4 hours of that we wake up.

Your serotonin side of things (with melatonin on its side) makes u sleep, the cortisol side of things with adrenaline and such makes you wake… this kinda gives insight into what you want to avoid at which times. Evenings should have more serotonin. Mornings can be more on the action side of things / stimulation based.

You do not wanna wake up during REM sleep if you can avoid it that seems to be bad too… so alarms may cause you more sleepiness too.

Another tip. After waking up. Wait out 30 min up to 2 hours till caffeine. You want that rest adenosine.. that excess sleepiness used up…that way you can kinda buffer that mid day sleepiness as you didn’t snow plow that adenosine around infront of the caffeine.

Source; Matthew walker (sleep expert) & Andrew Hubermann (neurologist) mainly