PS263 Lecture Notes - Lecture 8: Brainstem, Grothendieck Universe, Cholinergic
Document Summary
There are huge inter-species differences in the number of hours spent sleeping. Humans sleep on average 8 hours a day, but some animals sleep much more than that. The giant sloth, for example, sleeps 20 hours a day. Two general reasons why we might need sleep. One is related to recuperation theories of sleep, which suggest that being awake disrupts homeostasis (stability of the internal body environment) and that sleep helps restore this balance. Circadian rhythms (daily cycles of body function--such as sleep-waking cycle) theories of sleep suggest that the function of sleep evolved to conserve energy. Circadian theories provide a better account of the inter-species differences in amount of time spent in sleep. Ex: species that are more vulnerable to predation, such as cows or deer, spend less time sleeping, whereas predatory species such as lions spend quite a bit more time sleeping. 1. electromyogram (emg) which monitors the muscles, particularly those of the neck.
