A free, self-paced textbook in 7 chapters. Read a chapter, then drill it with the 202 companion flashcards using spaced repetition.
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 s...
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 s...
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...
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 Fahren...
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 movemen...
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...
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 t...