The mechanism: mast cells (the immune cells that release histamine among other things) have their own circadian clock. The CLOCK gene controls their IgE receptor expression in a time-of-day manner, and both plasma histamine and tryptase peak during the night. In healthy people this is fine. In MCAS or histamine intolerance, this nightly mediator release is excessive, and it happens right in the window where cortisol (which normally suppresses histamine release) bottoms out around 2-4am. Histamine is itself a wake-promoting neurotransmitter, so you get woken up, often by something minor like a noise, reflux, or a temperature shift that wouldn't otherwise register. Signs it might be worth looking into: 3am waking with a racing heart, sweating, flushing, itching, or reflux/throat tightness. A good in-depth resource: https://health.programmerlife.org/en/

As an avid reader of aircraft accident reports (ok, more reader of blog posts and watcher of YouTube videos based on those reports - yeah, people have strange hobbies), it reminds me more of flight data recorder graphs - the first FDRs actually inscribed the graphs with needles on metal foil (https://aviation.stackexchange.com/questions/59289/was-the-f...), which is of course no longer the case, but the presentation has been kept.

In my case, thinking too much about the causes of bad sleep actually contributed to making sleep worse, so if this guy is anything like me then this whole project could be hurting his sleep rather than helping.

I went to work at a BBB office once. They turned all their computers off at night and every morning they were back on. It was just "normal" for them.

I can't even remember what problem I was troubleshooting. At the time I was working on IVR systems.

Anwayz, I was working late in their office. Everyone had turned off their computers and went home. At exactly Midnight, every computer in the office turned back on.

I walked around the office looking at desks wondering what had happened. On one persons desk was an alarm clock with a very quiet alarm buzzing. I checked the clock and it was set for midnight (probably a default). About two minutes later it turned off automatically.

I turned off computers and re-set the alarm to go off a few minutes later.

When that alarm clock went off it somehow caused either draw or feedback in the wiring that caused all the computers to turn back on. At the time I wondered if it had something to do with wake on lan.

In any case, I suggested that person take their alarm clock home.

Also, iOS has background (white noise etc) sounds built-in: https://support.apple.com/en-us/109346 Android has something similar too?

We also installed triple-layered windows for sound insulation, but I believe it degraded the quality of the air, so sometimes have to open the windows for a few minutes before sleep to get fresh air.

Then correlate the time you woke up in your sleep log with the camera footage.

That’s not how lightning and thunder work.