Thermodynamics of Sleep
Summer arrived, and with it came the heat. Usually, this meant sleepless nights tossing in a pool of sweat on my memory foam mattress. Memory foam is notorious for trapping body heat; it’s like sleeping in a wetsuit. But down on the floor, things were different. Basic physics: heat rises. The air down near the floorboards was noticeably cooler—sometimes by 3 or 4 degrees—than the air at bed-height.
My cotton futon breathed. Air circulated through the straw of the Tatami mat. I slept cool and dry through the hottest nights of July without even turning on the AC. I learned later that a lower core body temperature is essential for deep REM sleep. By getting closer to the cool ground, I was naturally hacking my body’s thermoregulation. I wasn’t waking up dehydrated and groggy anymore; I was waking up fresh.