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Module 17 Sleep. Sleep. 1/3 of our lives Behavioral state Not a straightforward definition; reduction in physical activity, decreased response to stimuli, customary posture, easily reversible. Why do we sleep?.
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Module 17 Sleep
Sleep • 1/3 of our lives • Behavioral state • Not a straightforward definition; reduction in physical activity, decreased response to stimuli, customary posture, easily reversible.
Why do we sleep? • What evidence would a scientist need to determine the function/functions of sleep? • What is the best method for studying the function/functions of sleep?
Fatal Familial Insomnia http://www.youtube.com/watch?v=nIeTVVAEFn8
Sleepiness is Associated With… • Difficulty Concentrating • Memory Lapses • Loss of Energy • Fatigue • Lethargy • Emotional Instability
Functions of Sleep Theories • #1 Restoration/Recovery of Body Systems • #2 Energy Conservation • #3 Memory Consolidation • #4 Protection from Predation • #5 Brain Development • #6 Discharge of Emotions
How much sleep do you need? • You will probably spend 25 years sleeping! • What is your individual sleep need? (short sleeper vs. medium vs. long) • What is microsleep? How good are naps? • Do all species sleep?
Some Biological mechanisms involved • Hypothalamus –regulates body temperature and contains the “master switch for sleep” • Reticular formation and Pons – most likely respond to the hypothalamus and then shut down our attention • Thalamus – possibly coordinates brain wave activity(don’t forget pineal gland and melatonin!)
Measurements taken in a sleep lab Waves measured in frequency: cycles per second (cps) and in amplitude: the degree of the voltage changes from one location to another at that moment (EOG = eye movements)
Waking brain waves • Beta waves = alert and focused • Small in amplitude and fast in frequency (14 – 25 cycles per second) • Alpha waves = about to fall asleep; relaxed and thoughts drift • Larger and slower than beta waves (8 – 12 cycles per second)
Sleeping brain waves 80 % of sleep is NREM; 20 % is REM
Stage 1 aka Light Sleep • Heart slows; breathing may become irregular; muscles relax… *Hypnic jerk and hypnagogic trance • Waves are small and irregular mixed with some alpha waves • If you are awoken…
Hypnagogic Monument Melting Clock Salvador Dali Swans Reflecting Elephants
Stage 2 • Body temperature drops further • Sleep spindles appear (high frequency clusters) • If you are awoken…
Stage 3 • Delta waves start to appear (resemble coma EEG) =deep sleep *Largest and slowest waves (less than 4 cycles per second)
Stage 4 aka deep sleep • Around 1 hour • Almost pure delta waves • Most oblivious to external stimuli • From stage 4 you go to stage 3 to stage 2 to REM
REM • Paradoxical sleep – body is physiologically very aroused but voluntary muscles are paralyzed • Blood pressure and breathing wavers; sexual arousal (in terms of blood flow changes) • Waves are like beta waves; high frequency and low amplitude
When do you have the most deep sleep and when do you have the most REM?
Chart of NREM vs. REM • Quantity of dreaming? • Type of dream? • Wave types? • Increases after? • Body paralysis? • Timing in sleep cycle? • Eye movements?