You've most likely experienced the sensation of trying to drift asleep; you're fairly comfortable, then suddenly your arm, hand or leg will randomly jolt you awake.
This is what's called a hypnagogic jerk.
It's an involuntary muscle spasm that roughly 60 to 70 percent of us have experienced. It get its name because it usually happens when you're in a hypnogogic state - which is when you're in between being awake and asleep.
According to Live Science, some people have the random jerks while also experiencing hallucinations, the sensation of falling or bright lights from inside your head. While it most memorably happens while you're trying to drift off to sleep, it can happen several times while you're dreaming.
But usually, your significant other will be the one to tell you in the morning that you accidentally kicked or elbowed them.
It's believed that there are certain factors that can increase your likelihood of having a hypnagogic jerk: stress, anxiety, fatigue or sleep deprivation. Another theory is that it's a result of nerves misfiring as you're transitioning to sleep mode and your body is fearing that it's dying. A third theory relates to our ancestors, that the jerks are a form of ancient primate reflex that was supposed to stop us from falling out of trees.
Sleep is an incredibly fascinating area of study, especially dreaming, because the information around it is still evolving.
The siesta, the afternoon nap commonly found in Spain, has been associated with a 37 percent lower coronary mortality, improved sleep and cognitive tasks, as well as mental health in the elderly.
There are a few substances (anti-depressants, alcohol and ibuprofen) which decrease your mind's ability to dream, whereas melatonin is believed to be related to increased dream function.
Sigmund Freud's The Interpretation of Dreams in 1899, hypothesized that dreams are forms of wishful fulfillment and are attempts by the unconscious to resolve a conflict of some sort, whether something recent or something from the recesses of the past.
While recommendations vary from group to group, America's National Sleep Foundation says young adults should be getting between seven to nine hours of rest per night, and seven to eight hours for older adults.
Featured Image Credit: PATopics: Sleep