Chapter Eleven. Sleep and Waking

Transcription

1 Chapter Eleven Sleep and Waking

2 Sleep Are we getting enough. How z it work? Sleep Deprivation contributed to the Exxon Valdez, Challenger Explosion, and 3 Mile Island Deprivation is VERY common, and quite serious What cues us that it s time to get some sleep? Zeitgebers external light cues Variations in Sleep Patterns Night owls versus larks All Nighters lower your GPA, and lead to depression Shift Work, Jet Lag, and Daylight Saving Time Shift maladaptation syndrome; more errors & social issues Health issues include some serious stuff like breast cancer

3 Figure 11.3 Jet Lag is Worse When Traveling East

4 Circadian Rhythms Internal Clocks: the Master Clock is in the Suprachiasmatic nucleus (SCN) in the hypothalamus Regulates & responds to melatonin levels (tells animals that it s night NOT necessarily that it s time to sleep) Peripheral clocks influenced by activity levels (not light) Biochemistry and Circadian Rhythms Melatonin: secreted by Pineal Gland, sensitive to (suppressed by) light levels Cortisol: released by Adrenal Glands. Levels are highest in morning and diminish toward night Also influenced by stress levels and clinical depression

5 Figure 11.4 The Suprachiasmatic Nucleus

6 Figure 11.5 The SCN is Active During the Day

7 More on Circadian (and other) Rhythms Geography can make us SAD? Seasonal Affective Disorder Serotonin low and disrupted melatonin release patterns Treatment with UV light therapy, melatonin, antidepressants Is my brain off while I m asleep? Okay, waz up? EEG shows desynchronous activity (chaotic) Ultradian Rhythms (cycles) 90 to 120 minutes Five Stages of Sleep NREM 1-4, and REM for rapid eye movement Sleep timing associated with body temperature

8 Figure 11.7 Body Temperature and Hormone Secretions Follow Circadian Rhythms

9 Stages of Wakefulness and Sleep Wakefulness associated with Beta & Alpha waves Brain Activity During Sleep Alternating (90 to 120 minute) periods of rapid-eyemovement (REM) sleep and Non-REM (NREM) sleep Stage 1 NREM theta waves, myoclonia Stage 2 NREM sleep spindles, K-complex Stage 3 NREM less than 50% delta waves Stage 4 NREM more than 50 % delta waves REM beta rhythms much like wakefulness, plus increased heart rate, B.P., circulation to genitals, postural muscles are all paralyzed (thanks!)

10 Figure 11.8 Ultradian Rhythms Characterize Wakefulness in Humans

11 Figure Human Sleep Cycles

12 How much sleep to we need? Get? The amount and composition of sleep changes over the lifespan Newborns & Infants sleep hours per day and spend 50% of their time in REM Young kids sleep 9 hours a day, and spend some extra time in Stage 3 and Stage 4 NREM sleep At Puberty we decrease the amount of sleep we get, and spend less time in REM and Stage 3 and 4 NREM Adults (from age 50 on) get 27 minutes per decade less sleep per night (explains some aches and pains), even though our need for sleep doesn t diminish

13 Figure Sleep Patterns over the Lifespan

14 Dreaming During REM and NREM Dreams occur during both REM and NREM REM dreams vivid, story-like, unrealistic, and lengthy 70 % of dreams have negative emotional content NREM dreams short, logical, single image, no emotion Dream Theories Hobson & McCarley Activation Synthesis Theory Crick & Mitchison Forget irrelevant information Winson Integrate memories while asleep Nightmares: frequent in kids, happen in REM, paralysis Night terrors in NREM Stage 3 or 4, no paralysis, may hallucinate images into the room, often family history Antidepressants decrease the amount of REM sleep

15 Table 11.2 A Comparison of Night Terrors and Nightmares

16 The Functions of Sleep Sleep Keeps Us Safe: inactive & away from predators which may have better night vision Sleep Restores Our Bodies Growth hormone (GH); much higher levels released when we are young, but we get some even as aged old codgers Melatonin also released as we snooze Sleep Helps Us Remember Active role in Consolidation of memories Muscle & joint chemical restoration REM aids brain development and learning, and moderates our moods

17 Figure Predation, Shelter, and Sleep Patterns

18 Brain Mechanisms of Wakefulness and Sleep Ever fall asleep in class? Epic fail of wakefulness? Two pathways originate in the reticular formation of the medulla Signals travel to hypothalamus, hippocampus, basal forebrain, and the thalamus The first segment of sleep is Always NREM (almost) Let s chat about some features of REM Sleep now Rapid Eye Movements are associated with brainwave patterns like being awake, however we also get PGO (Pontine Reticular Formation + Geniculate Nucleus of Thalamus + Occipital Cortex) Spikes Activation of the Amygdala & Anterior Cingulate Cortex influence the emotional content of dreams

19 Figure PGO Waves Accompany REM Sleep

20 More about REM? And Sleep Disorders? An assortment of REM On areas in the Pons allow for inhibition of signals traveling to the spinal cord, so we get postural muscle paralysis (almost always) And now, about those disorders. Starting with Dyssomnias: Insomnia may be onset or maintenance related. Sleep Aid drugs add ½ hour of sleep time, but they are habit forming and have nasty side effects What about Sleep Apnea? LOUD snoring, stop breathing for up to 2 minutes. CPAP. Narcolepsy. Sudden irresistible sleep attack, and we go directly to REM high heritability quotient Cataplexy. Muscle paralysis while awake. May be minor (face) or major (all postural muscles)

21 More Sleep Disorders What about Parasomnias? Nightmares, Night Terrors & Sleep Walking, also known as Somnambulism. Sudden Infant Death Syndrome drastic drop in frequency when we put infants to bed face up. REM Behavior Disorder; can move during our dreams (no paralysis). Get away with murder?