We all know that a good night’s sleep helps us feel refreshed, right? You have a long, busy day that wears you out, then you go to bed and when you wake up the next morning, your energy has been restored. How exactly does that work?
As you might expect, when you try to explore the biology and chemistry behind sleep, it can be pretty complicated. Nothing about the human body is ever straightforward. A lot of the research into sleep and energy levels has focused on two chemicals in particular: adenosine and glycogen.
Adenosine builds up while you’re awake, and glycogen levels drop at the same time (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2948963/). It’s entirely possible that these two events are related, with one affecting the other. Sleep homeostasis is the name of the process where different chemicals increase and decrease in relation to our sleep and wakefulness.
As adenosine can be a byproduct of ATP (cellular energy) becoming depleted, and glycogen is responsible for energy storage in the brain, it’s clear this will have an impact on your overall energy.
If this is the case, and if sleep causes your adenosine to fall and your glycogen to rise, that may explain part of the restorative quality of sleep. It’s not a complete reason, and one thing sleep researchers have realized over the last century is that sleep is not remotely easy to explain, but it does put us a little closer toward understanding sleep homeostasis.
Other factors that impact our energy levels, like the amount of energy we take in through food in comparison to the amount of energy we expend through activity, can also be affected by sleep. Sleep can perform a balancing act not just for your brain but for all the other factors that impact how much energy is in your body.
That assumes you don’t have some kind of disruption to your circadian rhythms. Circadian rhythms are the reason most people sleep at night and wake during the day. People who are natural night owls have a different circadian rhythm controlling their sleep schedule. Disruption to circadian rhythms can damage the balance that sleep tries to create.
We might not know exactly how it works, but we need sleep to conserve the energy we have and to replenish what we’ve burned away. Even a short nap can be a valuable way to charge up.
