What’s the science behind someone being a “light sleeper”?
In: Biology
So as far as I’m aware, we actually still don’t have a like, comprehensive, in depth understanding of sleep. We’ve gotten some good ideas and all! Like we’re pretty sure that deep sleep phases are about energy saving and physical maintenance down time; and that the lighter and dream sleep phases have to do with memory. (I saw a fascinating study recently implying it’s about correctly associating emotional reactions and circumstances. They showed that when people had a “fearful” experience and slept poorly over the next week or so, they became more generally anxious; but if they slept well, they “correctly” associated the fear with its specific cause, such as a car crash or tiger chasing them, etc; and their general stress levels were unchanged.)
Anyways, sleep is *especially* complex and whole-brain, but here’s *a* hypothesis from someone that doesn’t really know neuroscience but would like to: there’s part of your “hindbrain” (the reptile brain, in that slightly outdated model) that continues to do some processing of senses while you’re asleep. I almost said that it “is still awake” while you’re asleep, but that’d be very incorrect, since being awake and conscious involves all kinds of other activity in the brain that you’re just not doing. The same part of the brain gets input from the ears (and other senses!) before it goes on to your full auditory cortex, and it handles startle reflexes, the way you’ll jump at a loud noise before you’ve fully put together what the noise is, where it’s coming from, etc. So this part of the brain “decides” (in a crude, simpler animal, or even mechanistic kind of way) if some input is worth startling you awake.
And so of course different hindbrains can be more or less “jumpy”, and can also care more or less about different things. I know mine sure fixates on the sounds of people talking or moving around; it just doesn’t feel safe if there are people around and it doesn’t know what they’re up to, so I’ve gotta wake up and listen. Hurricane though? Eh, we’ll sort that in the morning, if we’re still alive.
**ETA: TL;DR**: We aren’t sure, but it’s probably something like our hindbrain’s automatic startle/danger reflex activating.
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