What’s the science behind someone being a “light sleeper”?
In: Biology
Imagine a gate. On one side of the gate is a bunch of sheep (baa!). On the other side of the gate is a field of grass (yum). In this example, If a sheep gets to the grassy field, you begin to wake up.
The sheep are always trying to bump into the gate to get it open. When you’re awake, the gate’s just open. When most people are asleep, there’s someone pushing back on the gate each time the sheep bump into it, keeping it closed. For ‘light sleepers’ there’s still someone pushing back on the gate but they’re a bit weaker and so it’s easier for a sheep to bump open the gate and get into the field. Why are some gate-keepers weaker? For the same reasons people are just different. We’re born differently and we have different experiences and there’s nothing wrong with different.
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Taking this out of ELI5 territory, the sheep is the bombardment of sensory information to the brain, the field of grass is your body’s systems that begin to wake you up (e.g. the ascending reticular activating system, ARAS), the gate is a part of your brain called the thalamus (and generally the thalamocortical circuit of the brain), and the person at the gate are special brain waves called sleep spindles.
It is thought that the presence of sleep spindles affects the amount of sensory information from the body’s sense organs that go through the thalamacortical circuit and hence to the ARAS. It is thought that when sleep spindles are produced more frequently, sleep is less likely to be disturbed. As such, ‘light sleepers’ are would produce fewer sleep spindles during their sleep, hence, causing them to arouse more easily. There is also experimental evidence to support this hypothesis, as cited and referenced below. In the study, they found that the people who were more likely to wake up from a quieter noise (lighter sleepers) had less frequent sleep spindles than people who required a louder noise to wake them (heavier sleepers).
As another commenter points out, there are many factors that could affect these sleep spindle frequencies and to list them all would be too effortful for me. But sleep-wake disorders, genetics, various substances, and previous nights’ sleeps are just some of the things that can and do affect sleep spindle frequency
Answer based on this Cell journal article ([Dang-Vu, McKinney, Buxton, Solet, and Ellenbogen, 2010](https://www.cell.com/action/showPdf?pii=S0960-9822%2810%2900778-5)) and my 2019, undergraduate-level knowledge on sleep, which I found consistent to what is proposed in the article.
**References**
Dang-Vu, T.T., McKinney, S.M., Buxton, O.M., Solet, J.M., and Ellenbogen, J.M. (2010). Spontaneous brain rhythms predict sleep stability in the face of noise. *Cell*, 20(15), R626-R627. DOI: https://doi.org/10.1016/j.cub.2010.06.032
Edit: To anyone curious as to why this post was removed, this was a mod’s response. “It was removed because we don’t have the time and manpower to keep it clean to the level that is appropriate and it was inviting personal stories and medical advice.
I hope you appreciate the broad category removal reason, the “medical advice” one might technically be more accurate but doesn’t really make sense the way those removal reasons are phrased, does that make sense?”
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