Lecture 6 - 9/11/2009 Lecture 6 1. Sleep Ontogeny (Change...

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Unformatted text preview: 9/11/2009 Lecture 6 1. Sleep Ontogeny (Change across the lifespan - Humans) 2. Sleep Functions: Overview (Theories of why we sleep) Lecture 6 Sleep Ontogeny (Change across the lifespan) Lecture 6 Sleep Ontogeny • Sleep over the lifespan I: Total sleep amounts and patterns • Sleep over the lifespan II: WAKE : REM : NREM ratio changes • Sleep over the lifespan III: Architecture changes 1 9/11/2009 Lecture 6 Sleep Ontogeny • Sleep over the lifespan I: Total sleep amounts and patterns • Sleep over the lifespan II: WAKE : REM : NREM ratio changes • Sleep over the lifespan III: Architecture changes Lecture 6 Sleep Ontogeny Sleep over the lifespan I - early sleep patterns Newborn Infant = sleep Highly polyphasic sleep 1 year old 4 years old 10 years old Adult 6PM Lecture 6 Midnight 6AM Noon Time of Day 6PM Sleep Ontogeny Sleep over the lifespan I - early sleep patterns Newborn Infant = sleep Highly polyphasic sleep 1 year old Polyphasic sleep 4 years old 10 years old 6PM Midnight 6AM Noon Time of Day 6PM 2 9/11/2009 Lecture 6 Sleep Ontogeny Sleep over the lifespan I - early sleep patterns Newborn Infant = sleep Highly polyphasic sleep 1 year old Polyphasic sleep Biphasic sleep 4 years old 10 years old Adult 6PM Lecture 6 Midnight 6AM Noon Time of Day 6PM Sleep Ontogeny Sleep over the lifespan I - early sleep patterns Newborn Infant = sleep Highly polyphasic sleep 1 year old Polyphasic sleep 4 years old Biphasic sleep 10 years old Monophasic sleep 6PM Lecture 6 Midnight 6AM Noon Time of Day 6PM Sleep Ontogeny Sleep over the lifespan I - early sleep patterns Newborn Infant = sleep Highly polyphasic sleep 1 year old Polyphasic sleep 4 years old Biphasic sleep 10 years old Monophasic sleep Adult Monophasic sleep 6PM Midnight 6AM Noon Time of Day 6PM 3 9/11/2009 Lecture 6 Sleep Ontogeny • Sleep over the lifespan I: Total sleep amounts and patterns • Sleep over the lifespan II: WAKE : REM : NREM ratio changes • Sleep over the lifespan III: Architecture changes Lecture 6 Sleep Ontogeny Total Daily Amount of Sleep (hr) Sleep over the lifespan II – WAKE : REM : NREM ratio changes • 0-2 years old: High amount of total sleep, beginning high amounts of REM, increasing amounts of NREM Lecture 6 Sleep Ontogeny Total Daily Amount of Sleep (hr) Sleep over the lifespan II – WAKE : REM : NREM ratio changes • 2-20 years old: Decreasing total sleep, stabilization of NREM:REM ratio (4:1) 4 9/11/2009 Lecture 6 Sleep Ontogeny Total Daily Amount of Sleep (hr) Sleep over the lifespan II – WAKE : REM : NREM ratio changes • 20-90 years old: Decreasing total sleep (40-50yrs), stabile of NREM:REM ratio (4:1) *see architecture for details Lecture 6 Sleep Ontogeny • Sleep over the lifespan I: Total sleep amounts and patterns • Sleep over the lifespan II: WAKE : REM : NREM ratio changes • Sleep over the lifespan III: Architecture changes Lecture 6 Sleep Ontogeny Sleep over the lifespan III – Architecture changes Sleep Stages AWAKE Young Adult (~25yrs) REM NREM-1 NREM-2 NREM-3 NREM-4 5 9/11/2009 Lecture 6 Sleep Ontogeny Sleep over the lifespan III – Architecture changes Sleep Stages AWAKE Child (~7yrs) REM • Greater SWS amount • Few if any awakenings NREM-1 NREM-2 NREM-3 NREM-4 Sleep Stages AWAKE Young Adult (~25yrs) REM NREM-1 NREM-2 NREM-3 NREM-4 Lecture 6 Sleep Ontogeny Sleep over the lifespan III – Architecture changes Sleep Stages AWAKE Child (~7yrs) REM • Greater SWS amount • Few if any awakenings NREM-1 NREM-2 NREM-3 NREM-4 Sleep Stages AWAKE Young Adult (~25yrs) REM NREM-1 NREM-2 NREM-3 NREM-4 Sleep Stages AWAKE Elderly (~75yrs) REM • Absence of SWS • Increased awakenings • Reduced REM NREM-1 NREM-2 NREM-3 NREM-4 12am 1am 2am 3am 4am Time 5am 6am 7am Lecture 6 Sleep Functions: Overview (Theories of why we sleep) 6 9/11/2009 Lecture 6 Theories of sleep function: The old 1. Sleep is ADAPTIVE: - Sleep forces us to be quiet at certain times of the day, allowing us to share ecological niches with other species (**though many remote habitational species sleep) - Allows us to conserve energy - species with high metabolic demands sleep more (**though metabolism is high during REM. Furthermore, energy savings from sleep vs. lying still awake small relative to danger) [~slice of whole-wheat bread] - Allows us to avoid predators - rough correlation between predatory status and sleep properties (**though many animals are predator AND prey) Lecture 6 Theories of sleep function: The old 1. Sleep is ADAPTIVE: …e.g. elephants (who have few predators) only sleep for 2-4hrs Lecture 6 Theories of sleep function: The old 1. Sleep is ADAPTIVE: - Sleep forces us to be quiet at certain times of the day, allowing us to share ecological niches with other species (**though many remote habitational species sleep) - Allows us to conserve energy - species with high metabolic demands sleep more (**though metabolism is high during REM. Furthermore, energy savings from sleep vs. lying still awake small relative to danger) [~slice of whole-wheat bread] - Allows us to avoid predators - rough correlation between predatory status and sleep properties (**though many animals are predator AND prey) - Thermoregulation - alternating REM (warming) and NREM (cooling) may prevent overcooling (**but why to non-thermoregulatory species still sleep?) 7 9/11/2009 Lecture 6 Theories of sleep function: The old 2. Sleep is RESTORATIVE: - Sleep helps us to get back something we lose during waking – basic energy restoration: - Gives the brain time to replenish neuromodulators, remembering that Noradrenalin and Serotonin are inactive during sleep (REM) (**though no evidence these chemicals deplete, and what of ACh?) - Sleep helps repair and rebuild - growth hormone is only secreted during sleep (**though not in kids under 4, not in adults over 60 …times of needed repair?) - Furthermore, get only modest increases in SWS after times of presumed repair need e.g. ultramarathon. Also see little decreases in sleep in quadraplegics* * But see Huber et al. 2004 paper in later sections… Lecture 6 Theories of sleep function: The old 3. Sleep for DEVELOPMENT: - Young of all species who sleep, sleep the greatest amounts, and early life is the time of greatest neural development (**But why do we need to keep sleeping after we are fully developed?) - Perhaps it is not sleep per se, but specific stages of sleep, particularly REM – activating sleep, stimulating nervous system in utero when there is normally none i.e. endogenous trigger (**But why does REM persist throughout life when nervous system is fully developed?) Lecture 6 Theories of sleep function: The new Learning & Memory BRAIN Emotional Regulation Creativity & Insight SLE E P BODY Immune Function Metabolic Regulation 8 9/11/2009 Lecture 6 Theories of the functionS of sleep • No single theory of sleep function is completely satisfactory • Perhaps sleep is multifactorial -- originally evolved to serve one or a handful of functions, but now additional functions have piggy backed (adaptations) onto the sleep-state • Thus, some may never have been the original reason for sleep, but have been co-opted over time to take advantage of sleep. Lecture 6 Lecture 6 – Summary: Phylogeny • Sleep changes dramatically across the lifespan in numerous ways • Pattern of sleep begins as high polyphasic with large amounts ----> monophasic with less as we get older • WAKE:NREM:REM ratio also change within this altered pattern of sleep • Architecture of sleep changes: More consolidated, deeper SWS early in life, more fragmented and shallow late in life Lecture 6 Lecture 6 – Summary: Theories of why? • Old theories emphasized the need to sleep for: • Adaptive reasons: Energy conservation, Avoid predators • Restorative reasons: Repair body/cell, replenish brain chemicals • Developmental reasons: Trigger neural maturation • New theories emphasize the need to sleep for: • Brain: Learning & Memory, Emotional stability, Creativity • Body: Immune function, Metabolic regulation • Ultimate truth maybe is serves many different biological and psychological functionS - some it evolved for, some hitched a ride… 9 ...
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This note was uploaded on 10/05/2009 for the course PSYCH 133 taught by Professor Mathewwalker during the Fall '09 term at University of California, Berkeley.

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