The human body is a fickle thing. It can walk, run, jump, dance, push and pull without many repercussions at all. But sleep the slightest bit crooked, and it will be achy and sore for days. It makes you wonder, what really goes on in your sleep when you wake up feeling like the Rock used you as a hammer?
There are a few possible explanations.
The most plausible cause of soreness after sleeping is simply that when your body is twisted all weird for hours at a time, it puts strain on your muscles and joints, making them feel extra creaky in the morning. Beyond that, the overall lack of movement at night prevents lubricating fluid from flowing throughout your body, which would otherwise allow your bones to move past one another more comfortably. Without that fluid, a contorted sleep position can result in extraordinary stiffness.
Another possible origin of post-sleep achiness is that a lack of sleep can cause inflammation in the body, which can result in muscle and joint pain. So even if your body was in a fairly normal position throughout the night, if you were constantly in and out of sleep, that may interrupt the healing processes that your body normally activates during rest, and you can still wake up feeling like you just mud-wrestled the Hulk.
A couple other potential triggers for waking up achy are sudden movements while sleeping — you may move around in your sleep more than you think — or a previous injury that only started hurting after a day or two. So don’t rule out the possibility that your incessant slouching the day before is the real cause of your morning pain.
The good news is, combating post-sleep soreness is fairly simple. Tweaking your sleep position (sleeping on your back is best) and upgrading your mattress are both good starting points, and so is anything else you can do to improve your overall quality of sleep. But if you’re determined to sleep the way you already sleep, doing a reasonable amount of exercise — but not too much — during the day can help keep your joints lubricated so they stay loose and limber throughout the night, too.
See you (and your limber body) in the morning!