Key Terms
Consciousness
Awareness of internal and external stimuli. Circadian rhythm: 24-hour biological cycle.
Sleep
Low physical activity, reduced sensory awareness; distinct from rest during wakefulness. Wakefulness: high sensory aware
Biological rhythm
Internal cycle of biological activity. Circadian rhythm: biological rhythm occurring over approximately 24 hours.
Suprachiasmatic nucleus (SCN)
Located in the hypothalamus; the brain's biological clock.
Homeostasis
Tendency to maintain balance within a biological system. The hypothalamus is the main center of homeostasis.
Melatonin
Hormone released by the pineal gland.
Chronotype
Individual differences in circadian patterns (morning larks vs. night owls).
Jet lag
Symptoms from mismatch between internal circadian cycles and a new time zone environment. Includes fatigue, sluggishness
Rotating shift work
Work schedule that changes from early to late on a daily or weekly basis.
Treatment for disruption
Exposure to bright light during working shifts; dark exposure when not working. Helps realign the biological clock.
Sleep debt
Chronic sleep deficiency. Sleep rebound: faster sleep onset after deprivation; evidence of homeostatic regulation.
Sleep is also linked to
Creative thinking, language learning, inferential judgment, and emotional processing.
Sleep rebound
After sleep deprivation, a person falls asleep faster and sleeps more; evidence that sleep is homeostatically regulated.
Definition
Focusing on a single target (breath, sound) to achieve relaxed awareness. Can be done alone; hypnosis requires another p
Common pattern
Anxiety about not sleeping increases arousal, which makes sleep harder. Self-perpetuating cycle.