The Dark Reality of What Happens When You Close Your Eyes

Why does one foot always end up outside the blanket? That's your body's radiator, and it's one of 12 things your body does while you're asleep. Sleep science explained with a stickman in 10 minutes. CHAPTERS 0:00 - What happens tonight 0:48 - The paralysis switch 1:33 - Acting out your dreams 2:05 - The wakings you forget 2:40 - The night rinse 3:21 - The foot out the blanket 4:03 - Sleep talking 5:13 - The replay 5:51 - The repair shift 6:13 - The dreams you lose 6:51 - False awakenings 7:24 - Exploding head syndrome 7:52 - The monster on your chest Kevin thinks he's going to get a good night's sleep. Kevin is wrong. Sleep isn't you switching off. When you shut your eyes you enter a full sleep cycle in which your brain runs maintenance it cannot run while you're using it — flushing waste out through the brain's own fluid, repairing tissue, and replaying the day's events at speed. It's a nightly routine far more active than it looks from the outside, and occasionally it glitches: REM sleep phenomena like sleep paralysis, where your mind wakes up but your body stays frozen, or the hypnagogic crash of exploding head syndrome. Understanding the biology is what explains why so many cultures built myths about a monster sitting on your chest. In this video: REM atonia and why your body paralyses itself every night, REM sleep behaviour disorder and people who act out their dreams, the dozen times you wake up and forget, the glymphatic system and how your brain washes itself out, why your core temperature drops and your foot ends up outside the blanket, sleep talking and somniloquy, memory replay and how your brain re-runs your whole day at speed, growth hormone and why children really do grow in their sleep, why you forget almost every dream, false awakenings, exploding head syndrome, and sleep paralysis. the one that roughly 1 in 12 people experience, and that nearly every culture on Earth built a monster to explain. None of this means something is wrong with you. Sleep isn't time off. It's the shift where everything gets fixed — and you're not invited. 💬 Which of these twelve has happened to you? Tell me in the comments. If it's number twelve, you're in very large company. STUDIES MENTIONED Xie et al. (2013), University of Rochester · Wilson & McNaughton (1994) · Schenck & Mahowald · Takahashi et al. (1968) · Kräuchi et al. (1999) · Sharpless & Barrero (2011) · Sharpless (2015) ABOUT INSIDE KEVIN'S HEAD Simple stickman animations explaining the weird things your brain and body do every single day. Psychology, brain facts and human behaviour in plain English — backed by real studies, and always at Kevin's expense. 🧠 New videos every Monday and Thursday.