It doesn’t really do anything to restore energy, more that it slows the rate at which you use up your current energy reserve, so if the goal is to ultimately recharge your batteries it is pretty much a “useless gesture”.
There’s some discussion around the idea that a deep meditative state can give the feeling of energy being restored, but it’s not really been proven scientifically, it’s likely more a perceived effect not unlike a placebo.
As someone who has severe trouble falling asleep I figured out that by lying all night in my bed and doing nothing I will rest and get some energy back. More physical energy than mental, but it roughly translates into half or a quarter of the sleep time, say I couldn’t sleep and was 6 hours in my bed awake, that feels (at least for me) like 2-3 hours of sleep. IMPORTANT: doing anything else on the side, like listening to music or a podcast, a show in the background etc. will diminish the resting effect almost completely.
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