W7 Lecture: Sleep PDF
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Uploaded by FelicitousKazoo7765
University of Sydney
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Summary
This document discusses various aspects of sleep, including sleep patterns in different animals, the effects of sleep deprivation on health, the neural mechanisms that regulate sleep, and REM sleep. It covers the roles of different brain regions in sleep regulation and explains how drugs can affect sleep cycles.
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# W7 Lecture: Sleep - Everyone sleeps, even jellyfish and worms. - Sleeping patterns per animal vary greatly based on a number of physical factors. - Sleeping = opportunity cost/vulnerable (most animals sleep at night) - Birds and aquatic animals sleep with half their brain at a time (e.g. dolphins...
# W7 Lecture: Sleep - Everyone sleeps, even jellyfish and worms. - Sleeping patterns per animal vary greatly based on a number of physical factors. - Sleeping = opportunity cost/vulnerable (most animals sleep at night) - Birds and aquatic animals sleep with half their brain at a time (e.g. dolphins) ## Sleep and Health - Helps all cognitive functions. - When deprived, mood/function/speed/attention/memory all affected negatively. - Deprivation leads to eating/obesity (auto diabetes). - Affects ghrelin, leptin, and insulin. - Impacts all parts of you, even the sympathetic nervous system. - The day after daylight saving time, there are 20% increase in heart attacks on that day. ## What keeps us awake? - All of norepinephrine in the Locus Coeruleus (all in the brain stem) - Serotonin in Raphe nuclei - Acetylcholine in pons. - Neurons in this part are much more active while awake than asleep. - Drugs mimic these neurons like ecstasy or cocaine. ## What sends us to sleep? - Pre-optic Area (anterior hypothalamus) is responsible for sleep. - The neurons here contain GABA. - GABA inhibits actions, while we are awake. - The longer we are awake, the more adenosine. - Adenosine builds up in the brain. - Increases sleepiness by inhibiting alertness centers and stimulating sleep centers. - Caffeine blocks adenosine receptors. - Suprachiasmatic nucleus controls the release of hormone melatonin from pineal gland. - Melatonin signals night-time to the body, right above the brain stem. ## Sleep Cycles - EEG when sleeping: - Brain waves while awake: - Waves get more slow the deeper sleep (slow wave sleep) you get into. - Thalamus is coordinating the slow wave sleep due to being connected to the entire brain through 2-way communication (both incoming and outgoing). ## REM Sleep - Brain waves: Look the same as awake. - If woken up during REM sleep, we report we were dreaming. - Amount of REM increases during the night. - Decreases across lifespan: - 50% newborn, 20% adults - Drugs for sleep and alcohol negatively affect REM sleep. ## Brain Regions - REM sleep caused by neurons in Pons that acetylcholine and stimulate neurons in the thalamus which project to the visual cortex. - With fMRI: - During REM: - Active areas: - Visual regions at frontal lobes. - Back of brain. - Suppressed areas: - Motor regions - lateral prefrontal cortex. - Limbic system. - We are paralyzed during REM sleep. - Ach neurons in Pons stimulate neurons (in medulla), which ultimately inhibit motor neurons in spinal cord paralysis (except for eyes). - Destruction of these neurons in medulla cause us to act out our dreams during REM sleep. ## Neural Mechanism of Reward - Discovered an accident by placing electrode in the wrong spot - medial forebrain bundle (MFB). - MFB: Bundle of noradrenaling and dopamine fibers traveling from brainstem to forebrain. - Dopamine in MFB makes greatest contribution to rewarding effects. - Many addictive drugs directly boost release of dopamine in MFB.
