Hacker News Reader

There’s no clear set of genes that causes delayed sleep. You definitely have those rare mutations of core clock genes which causes their circadian cycle to have distinct properties, one of the outputs of which is a natural sleep preference that’s out of phase with typical societal rhythms, but is still a normal amount of sleep, and its consolidated and restful etc.

But the clock itself has a population wide variation in its actual period. It varies between 23.8 hours and 24.6 hours, and everyone far from the 24 hour ideal pays a tax. The clock either has to phase advance or phase delay to synchronize, and over time that has all kinds of impacts, including on sleep, but also memory and learning, stress, attention…

The whole system is clocked. Every cell in our body runs a 24 hour cycle, driven by the transcription, translation, inhibition and breakdown of the core clock proteins. They’re in a negative feedback loop, with a time delay, and all kinds of mutations can shift the overall period of the clock. If it’s of a core clock protein, the effect will be strong, but other genes cycle or have their functions in a cycle due to the clock, and feed back into the clock, so small mutations can accumulate to cause circadian period variation.

It’s also why you see circadian phenotypes in all kinds of diseases. Definitely needs more research, but the research is also hard. You need to observe the body in high resolution over many time points to start making sense of all this, and that’s expensive and exhausting. We’ll get there, though.

> It varies between 23.8 hours and 24.6 hours, and everyone far from the 24 hour ideal pays a tax.

As a person with ADHD and who noticed that whenever I have a few weeks off (so no schedule restrictions, so to speak) my sleep schedule seems to advance by almost an hour a day, this sounds like it might explain a few things.

Yeah if I allow it my sleep schedule shifts about 45 minutes a day. Eventually it'll "flip" my day after a month or so instead of going to bed late now I'm getting up early. However it also feels like not all the biological rhythms follow it.

That’s the endogenous period, that really only comes out as is in total darkness over many days. If the hour a day shift keeps happening even when you have access to sunlight, that would be interesting, though I’m not a clinician. Does the activity pattern drift till you’re in anti-phase to the solar day?

Generally the endogenous clock is approximate (hence the word circadian, about a day). But that’s because the day length has been constantly lengthening since animals evolved. Too slowly for us to notice, but the proteins that handle clocking are fairly ancient (though there are additional copies in humans compared to a fruit fly, say), and they aren’t locked in to favor a rotation period for Earth because there hasn’t been a stable period over long stretches.

The clock entrains to the environment, though. The more the daylight brightness to night time darkness shift in intensity, the higher amplitude their rhythms are, generally. Other signals also entrain them, like social activity, and the gut clock is a whole other complexity (kinda downstream of the brain clock but it can feed right back and wreck the central oscillation).

Any number of these factors can cause circadian effects, from a flatter rhythm, changed period, entrainment mismatch, etc.

In rare cases when a circadian gene itself is mutated, then you can have the clock period stretched significantly, and then synchronizing to the 24 hour day becomes really hard.

> The clock entrains to the environment, though. The more the daylight brightness to night time darkness shift in intensity, the higher amplitude their rhythms are, generally.

Well, this is also interesting, because I was born in Ghana and spent the first four years of my life there, and since then have always had insomnia issues, first in the Netherlands and now Sweden. However, the one time I visited Ghana as an adult for a month I slept like a baby.

I actually had a gut feeling that the much quicker shift from day to nighttime darkness and back played a big part in it, but wasn't sure why that might be the case. I assumed it was psychological somehow, that on some subconscious level I felt more "at home" in Ghana's natural environment because it's what my brain was "calibrated" on in the first years of its life. Would be interesting if that actually is the case in a circadian rhythm sense.

> That’s the endogenous period, that really only comes out as is in total darkness over many days.

And speaking of Sweden, I wouldn't be surprised if the short winter days probably do give enough "leeway" to approximate that effect.

Creative types often have sensory differences and staying up at night helps alleviate the overload that intense sunlight and people cause.

I know because I am on the spectrum and suffer from overload. At night is my "flow time" when the creativity happens.

The night is my best time too, but I’d hesitate to say that for most folks this has to do with the night being quieter.

The clock just has that spread. And I’d argue it makes evolutionary sense. You want people who are alert later, in a group. But this holds for most animals too.

In my case I interpret it as my "safe time". At night, the world sleeps, and no one is waiting on me, or going to randomly interrupt me. When other people sleep, obligations sleep too.

No? I guess I can't speak for most, but one of the things I most notice being different, other than the light of course, is the noise.

Autism correlates with specific neanderthal genes. There is a hypothesis that neanderthals were nocturnal based on the larger eyes and visual cortex.

I have had the opposite effect. The days where I get 8 hours of good quality sleep per Oura and Garmin have been some of my least productive days, which is always contrary to my expectations. My most productive and focused days are usually when I get 5 hours after a few nights of solid sleep. It might relate to the hangover effect, but I've never really been hung over before so I don't know if that would affect me.

Ha! Same. But it’s not sustainable. I need the long reset for the short one to work

> after a few nights of solid sleep

Can't speak for you but at least myself I find there's a delay of 24 to 48 hours before either sufficient or lack of sleep really catches up with me. It takes 2 to 3 nights of good sleep (unfortunately somewhat difficult to pull off) before I feel fully functional.

I did not see environmental factors in your consideration.

I got ADHD and Autism diagnosed as teen, the diagnostic was rather solid. Got methylphenidate for some months. I ran away from home with 17, i moved together with my girlfriend (at 26) into an emotionally stable environment and... the symptoms disappeared. No jactation, no special interests, no masking. Everything just disappeared. A bit of stimming remains. And a horribly fucked up sleep cycles.

Had undiagnosed RAD and CPTSD for longer than i'm self-aware. Severe emotional neglect for my first 17 years. Parental rejection plays a big part in here.

I'd be like, maybe i'm just a special case, and nothing of this applies to other people. But i see other ADHD-havers being too similar to me, and that includes hypervigilance and silent walking, which are apt adaptions to certain kind of childhood environments.

Maybe too much gets diagnosed as ADHD that is not genetic at all...

CPTSD literally rewires your brain and "appears" in diagnostic tests as ADHD: lower arousal in prefrontal cortex, overactive amygdala causing fast emotional response, impacted hippocampus, dopamine disregulation, etc.

Stress changes the layout of your brain along with your body's chemical responses. With ADHD, genetics seem to play a larger role where you can lack the stressors and still end up with the same end result. I wouldn't be surprised that treatments would work across both CPTSD and ADHD.

> CPTSD literally rewires your brain and "appears" in diagnostic tests as ADHD

This seems unexpectedly one-sided to me. It could equally be that ADHD is CPTSD from something that current knowledge does not consider traumatic (yet).

The highly heritable aspect of ADHD makes that proposal a bit weird

CPTSD is inheritable by child rearing. Thats what makes trauma intergenerational. Runs through families like cluster B disorders.

Edit: I think in practice this looks like normalisation of neglect and violence within a family.

I am not sure the distinction goes in this direction. Rather than "shouldn't be diagnosed as ADHD" I would sooner say "ADHD should be treated in multiple ways"

It's very typical for there to be overlap between inevitability and environmental circumstances

The distinction might be useful for determining whether to prescribe stimulants. People with CPTSD should not get those.