202 cards
Sleep is a reversible, naturally recurring state of reduced responsiveness and altered consciousness, distinct from unconsciousness in that a sleeper can be aroused. Modern sleep science divides sleep into two main types: REM (rapid eye movement) and NREM (non-REM). NREM is further subdivided into three stages. N1 is t...
Sleep needs vary considerably across the lifespan. Infants require the most, around 14 to 17 hours per day, while toddlers need 11 to 14 hours including naps. School-age children should get 9 to 11 hours, and teenagers 8 to 10 hours. Most adults need 7 to 9 hours per night for optimal functioning, and seniors can usual...
The body's master clock is the suprachiasmatic nucleus, or SCN, a small region in the hypothalamus that orchestrates circadian rhythms throughout the body. Light is the SCN's most powerful input: bright light, especially the short-wavelength blue light emitted by phones, tablets, and LEDs, suppresses melatonin producti...
Sleep hygiene refers to the behaviors and environmental conditions that support healthy sleep. The bedroom should be cool, dark, and quiet: a temperature of 60 to 67 degrees Fahrenheit (15.6 to 19.4 degrees Celsius) helps the body achieve the natural drop in core temperature that precedes sleep. Darkness supports melat...
Sleep can be measured in several ways. Polysomnography, or a sleep study, is the gold standard: an overnight test that records brain activity, breathing, heart rhythms, and movement. Home sleep testing offers a simpler alternative focused on breathing but may miss some conditions. Wrist-worn actigraphy estimates sleep...
Sleep is foundational to nearly every system in the body. During NREM slow-wave sleep, the brain's glymphatic system becomes highly active, with cerebrospinal fluid flow increasing to clear metabolic waste products, including amyloid-beta, a protein implicated in Alzheimer's disease, which is one reason chronic sleep d...
When sleep is difficult, several evidence-based strategies help. Cognitive Behavioral Therapy for Insomnia, or CBT-I, is the first-line treatment for chronic insomnia, addressing the thoughts and behaviors that perpetuate poor sleep. Its components include stimulus control, which re-associates the bed with sleep throug...