SLEEP
We need sleep just like we need food and water. Our internal clock regulates our sleep patterns according to the 24 hour cycle of light & dark which is why we usually feel sleepy every 12 hours (i.e., around 2-4am and 2-3pm).
How much sleep do I need?
Everyone has their own "sleep number" but 90% of adults need 6-8 hours EACH NIGHT. But, just like there's an exception to every rule, some people can get by on as little as 5 hours a night while others need more than 10 hours. To figure out your real sleep number wake up without an alarm clock for 3 consecutive nights & then take the average number of hours of sleep you got.
What happens during sleep?
During the night, we go through 4 or 5 sleep cycles which last 90 minutes each. In every cycle, we go through REM (i.e., rapid eye movement) and non-REM (i.e., stages 1-4) states which allow our brains & muscles to regenerate. Non-REM sleep regenerates parts of the brain responsible for speech, creative thinking, judgment, impulse control, attention, and visual association while REM sleep is responsible for stimulating the part of our brain used for learning and memory.
During a typical night of sleep, adults spend more time in REM sleep near the end of the cycle. If we’re consistently getting less sleep than we need, it will start to impair our learning and memory.
