From the Nightmare On Elm Street movies where the killer finds his victims in their dreams, to the myth that we accidentally swallow spiders while we snooze, the vulnerability of sleep has intrigued the waking mind for generations.
And although our imaginations far outstrip reality, there are still plenty of weird things that go on while we are sleeping.
From snacking to bladder control, here are a few surprising things that can happen to your body while you slumber…
1. Sleep-eating, sleep-talking, and sleep-signing
Everyone has heard of sleep-walking, but there’s a whole raft of activities some sleepers can find themselves undertaking while their consciousness is out for the count.
Sleep-eating disorders may see somnambulists head to the fridge for a midnight snack, sleep-talkers can hold coherent conversations, and sleep-signing is sleep-talking for deaf people. There’s also a condition called sexsomnia, which you can probably work out for yourself.
2. Your brain physically logs your memories
There’s a broad belief that your brain shuts down when you sleep. Far from it, your noggin spends slumber sorting and cataloguing the memories you accrued during the day, consolidating them as long and short term iterations in different parts of the brain.
At some point, most of us have pulled all-nighters to memorise a presentation, or revise for an exam. It probably wasn’t very productive.
3. Your body releases a hormone that stops you needing to pee
The average person urinates six or seven times a day, and although getting up to go to the bathroom is hardly unusual, comfort breaks proportionally fall much more in daylight hours. As night approaches your body clock releases extra ADH (antidiuretic hormone), which inhibits the production of urine.
That’s why we (mostly) don’t wet ourselves overnight, and almost always need to relieve ourselves come morning.
4. Rapid eye movement
You’ve probably heard of rapid eye movement (if just from the rock band REM), and it’s so strange that we’re glad we only experience it asleep. Your pupils jerk back and forth at alarming speed beneath your lids as if suffering from demonic possession, often accompanied by vividly abstract dreams.
Neural activity in the brain at this time is similar to that during waking hours, and your muscles even experience low level contractions.
5. Exploding head syndrome
OK, we admit, we included this one mostly for the name. Mercifully nothing to do with actual exploding heads, sufferers are prone to hearing imaginary, but extremely loud bangs while entering or emerging from deep sleep. It’s not dangerous, and is typically sporadic, but by God can it give you a fright.