Across
- 3. Deepest stage of sleep with lowest heart rate and breathing
- 6. Biological rhythms occurring more than once per day
- 7. Brief dreamlike hallucinations occurring in early sleep
- 9. The repeating 90-minute pattern of sleep stages
- 12. The body's 24-hour biological clock
- 13. Brain structure that regulates circadian rhythms
- 15. Brain waves associated with being awake and alert
- 16. Short bursts of brain activity in Stage 2 sleep
- 18. Disorder with sudden sleep attacks and excessive daytime sleepiness
- 19. Moving around while still asleep
- 20. Intense frightening episodes occurring during deep sleep
- 21. Sleep stage making up about 50 percent of total sleep time
Down
- 1. Hormone that regulates sleep-wake cycles
- 2. A dream where the sleeper is aware they are dreaming
- 4. Sleep stage where vivid dreaming occurs
- 5. Theory that sleep helps the body repair itself
- 8. Brain waves associated with deep sleep
- 10. Theory that dreams are the brain making sense of random neural activity
- 11. Hidden meaning of a dream according to Freud
- 14. Disorder where breathing repeatedly stops during sleep
- 17. Measures electrical activity in the brain