# Shortform-Why We Sleep  Author:: Matthew Walker ## Highlights > (Shortform note: Blue light may have an even bigger impact on children, as they’re more sensitive to light and have bigger pupils.) > plaques. (Shortform note: A study suggests that sleeping on your side can help decrease the chances of developing Alzheimer’s and other neurological diseases.) > Shortform note: The National Institute on Aging says that older adults needing less sleep is a common misconception. Older people still need seven to nine hours of sleep a night.) > Shortform note: Walker indicates five stages of sleep—one stage of REM and four stages of NREM—but other sources such as the American Academy of Sleep Medicine, the Sleep Foundation, and the National Institute of Neurological Disorders and Stroke say there are four stages: NREM 1, the point of crossing over from wakefulness to sleep; NREM 2, when your heart rate slows and eye movements stop; NREM 3, deep sleep; and REM, the dream state.) > NREM, characterized by slow electrical activity in the brain, clears out old memories and mental “trash,” and moves information into long-term storage.REM is characterized by faster, frenetic brain waves. It strengthens the valuable information that remains, and it forges creative novel connections between them. During REM sleep, your sense of time is dilated, you consciously perceive your senses, and you experience muscle atonia (your voluntary muscles are completely limp) to prevent you from acting out your dreams. > Shortform note: It’s best to avoid pulling an all-nighter, but if you must, you can minimize the disruption to your sleep routine by keeping yourself awake until your next bedtime. Stay hydrated, and resist the urge to take a long nap—stay active, chew gum, or smell rosemary, peppermint, or coffee to help keep you up.) --- Title: Shortform-Why We Sleep Author: Matthew Walker Tags: readwise, books date: 2024-01-30 --- # Shortform-Why We Sleep  Author:: Matthew Walker ## AI-Generated Summary None ## Highlights > (Shortform note: Blue light may have an even bigger impact on children, as they’re more sensitive to light and have bigger pupils.) > plaques. (Shortform note: A study suggests that sleeping on your side can help decrease the chances of developing Alzheimer’s and other neurological diseases.) > Shortform note: The National Institute on Aging says that older adults needing less sleep is a common misconception. Older people still need seven to nine hours of sleep a night.) > Shortform note: Walker indicates five stages of sleep—one stage of REM and four stages of NREM—but other sources such as the American Academy of Sleep Medicine, the Sleep Foundation, and the National Institute of Neurological Disorders and Stroke say there are four stages: NREM 1, the point of crossing over from wakefulness to sleep; NREM 2, when your heart rate slows and eye movements stop; NREM 3, deep sleep; and REM, the dream state.) > NREM, characterized by slow electrical activity in the brain, clears out old memories and mental “trash,” and moves information into long-term storage.REM is characterized by faster, frenetic brain waves. It strengthens the valuable information that remains, and it forges creative novel connections between them. During REM sleep, your sense of time is dilated, you consciously perceive your senses, and you experience muscle atonia (your voluntary muscles are completely limp) to prevent you from acting out your dreams. > Shortform note: It’s best to avoid pulling an all-nighter, but if you must, you can minimize the disruption to your sleep routine by keeping yourself awake until your next bedtime. Stay hydrated, and resist the urge to take a long nap—stay active, chew gum, or smell rosemary, peppermint, or coffee to help keep you up.)