CHAPTER 15. Sleep and Consciousness Sleep and Dreaming. Why do we sleep?. Why do we sleep? Long unanswered question We know consequences of NOT sleeping, but not understand why we must sleep Two major theories regarding function of sleep Restorative hypothesis
Sleep and Consciousness
Sleep and Dreaming
The suprachiasmatic nucleus: The nuclei, indicated by the arrows, took up more radioactive 2-deoxy-glucose in the scan on the left because the rat was injected during the day; the rat on the right was injected at night.
somnolence or drowsy sleep: transition of the brain from alpha waves to theta waves
Sudden twitches and hypnic jerks (positive myoclonus) associated with the onset of sleep during N1.
may also experience hypnagogic hallucinations during this stage , which can be troublesome
Individual loses some muscle tone and most conscious awareness of the external environment.
characterized by sleep spindles ranging from 11 to 16 Hz (most commonly 12–14 Hz) and K-complexes.
muscular activity decreases,
conscious awareness of the external environment disappears.
This stage occupies 45% to 55% of total sleep in adults.