What are these second-long 'surges' I'm having before sleep when crashing

Another very hard to describe phenomenon. I get this when I'm crashing. Perhaps half-a-dozen times a year. It only happens in bed when I'm led waiting to fall asleep. I get this bizzare second-long surge that I can feel in my head (possibly traveling up to head from torso). I'm sure it's not an adrenaline rush as it's not triggered by anything and there's no panic/anxiety or raised heart beat, though my heart can beat a little harder. It might happen once, or it might repeat a few times (spaced out by 10 minutes or so) before I get to sleep. It really freaks me out and I'd love to know what's going on. It feels like a chemical or hormonal release.

Anyone experienced this, or anything similar?

 

Might be what's called a "hypnic jerk." It's fairly common. I've experienced it a few times and it is pretty weird.

 

I get those, but they do not appear to be what @InitialConditions is describing.

 

I used to get hypnic jerks. I also had Exploding Head Syndrome.

Thankfully I appear to have aged out of both these conditions, although I think that improving both these conditions may have been speeded along by improving my nutrient levels, something I did by myself without the aid of doctors.

Edit : Fixed my link, which didn't work.

 

Just as a suggestion... I've read that many people with ME have proven low cortisol. I don't know the biochemical connection between cortisol and adrenaline, other than they are both produced by the adrenal glands and are both stress hormones. But perhaps if you have a low level of either of them one or both may occasionally rise just for a few seconds, and if you are used to a low level and it rises then it may be interpreted as a kind of rush? I think adrenaline may be produced when necessary, but cortisol is produced in a circadian rhythm, so it rises at certain times of day without an obvious trigger.

In healthy people I think the trigger for maintaining the circadian rhythm is sunlight, but if you spend a lot of time in the dark perhaps your circadian rhythm is disturbed.

 

Your real problem is that you're trying to not fall out of a tree in your sleep Wikipedia says so, so it must be true. Plus I like that explanation better than the usual - equally unproven - suspects of anxiety and stress.

https://en.wikipedia.org/wiki/Hypnic_jerk

I don't get jerks but quite often just at the point of going to sleep I get a weird sensation of an "awakeness hormone" being flushed through my body for just a second. Then I feel awake for a little while until becoming drowsy again and either going to sleep or repeating the experience. It's a quite pleasant, relaxed sort of alertness, not at all wired and tired, and during the day it would be welcome, just not when I want to sleep.

I've always assumed it's an odd, non-jerking version of hypnic jerk but that's just a guess that suits me because while hypnic jerks are annoying at least they're harmless.

 

Thanks for your comments. It's not a hypnic jerk - I do experience these and it's very different. These surges are totally within my body, and feel like a release of a hormone or chemical(?) @NelliePledge 's experience is the most similar to what I'm describing.