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Characteristics and patterns of sleep


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Key concepts: Characterisitics and Patterns of Sleep

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Characteristics and patterns of sleep

  1. 1. Lesson 4: Measuring Physiological Responses Exam Question: Ella loves Yoga. She finds it relaxing and it helps her to deal with the stressful activities of her day. a) What brainwave pattern would Ella show during a Yoga session? Explain your response. b) Which device would best measure Ella’s brainwave pattern? Explain your response. Hint: her brainwaves look similar to this ~>
  2. 2. Model Responsea) Alfa waves because Ella is in a meditative state, awake but very relaxed, which is associated with reasonablyhigh frequency (but not as high as beta waves) and low amplitude (but slightly higher than beta waves) brainwaves. b) An Electroencephalograph (EEG) because it detects, amplifies and records electrical activity in the brain in the form of brainwaves.
  3. 3. Is th is or pu .... p p .... o .... ss .. ? es ??? sed
  4. 4. Characteristics of Sleep
  5. 5. NREM Sleep Non-rapid eye movement sleepNREM sleep includes those stages not associated with rapideye movements. Adults spend approximately 80 percent oftheir nights sleep in NREM, and typically the first half of thenight has more NREM sleep than the second half.NREM is essential to the physical growth and repair of thebody. Research has found the amount of NREM increases aftervigorous exercise (Vein et al., 1991).NREM is dream free about 90% of the time, dreams tend to bemore short lived and fragmented than those in REM.
  6. 6. NREM Stage 1~Theta waves, which are of lower frequency and higher amplitude thanalpha waves, appear and start to replace alpha waves.~Despite the fact that various wave types are shown in this stage, thetawaves define Stage 1 NREM sleep.~In stage one of sleep, breathing becomes irregular, muscles relax, andhypnic jerks often occur.~Stage 1 lasts for approximately 2 min.
  7. 7. NREM Stage 2~In this stage there is a prevalence of theta-wave activity.~ As sleep deepens EEG recordings begin to pick up unique brain wavefeatures that are characteristic of stage 2 sleep. Theses include• Sleep spindles – brief bursts of higher frequency brain waves• K complexes – single sharp bursts (rise then fall) in amplitude (and lower frequency).• Body temperature decreases~Stage 2 sleep lasts for approximately 20 min
  8. 8. NREM Stage 3~Delta waves begin to appear which arelarge and slow.~Stage 3 is a transitional stage andlasts for approximately 2 min.
  9. 9. NREM Stage 4~Brain waves become almost pure delta waves~Regular (slow) heartbeat, slow (rhythmic) respiration &little muscle activity~Possible occurrence of night terrors~Very hard to awaken a sleeper from Stage 4 sleep.
  10. 10. REM ~ Rapid Eye Movement~REM sleep is strongly associated with dreaming. About 85% of the timea person is awakened from REM sleep they report vivid dreams.~On average REM sleep totals about 90 min per night. The amount ofREM sleep tends increases with stress in an individuals life.~REM sleep is sometimes called paradoxical sleep, as aspects of REM sleepappear to contradict each other. The brain wave pattern is very much likethose produced during alert wakefulness. The bodies internal functioningis more active during REM sleep than during NREM sleep, the heart beatsfaster, breathing is more rapid and irregular, and genitals becomearoused. On the other hand, the sleeper is totally relaxed; most of theskeletal muscles are totally relaxed (to the point of paralysis).
  11. 11. Patterns of SleepAn adult sleeps for approximately 8 hrs per night progressing through cycles of about 1.5hours. Periods of deep sleep (NREM4) occur earlier in the night, and periods of REM sleep occur,on average every 90 minutes.Adults experience a total of 1-2 hours REM sleep a night, in 4-5 sessions, each progressing inlength.The period of total REM sleep lessons as individuals get older. A newborn spends approximately50% of total time in REM sleep compared to an adult who spends approximately 20% of theirtime in REM sleep.
  12. 12. WHY DO WE SLEEP?
  13. 13. Survival Theories Focuses on when and why different species sleep Sleep depends on the need to find foodSleep depends on an animal’s vulnerability to predators Sleep conserves energy
  14. 14. Limitations of Survival Theories Survival theories fail to explain why we MUST sleepSurvival theories state that sleeping offers security from predators, however the loss of awareness while asleep contradicts this statement.
  15. 15. Focuses on why sleep is important The neurotransmitters adenosine (energy), norepinephrine (alertness) Immunity to diseaseGrowth hormones Restorative Theories MetabolismSleep enhances mood Sleep repairs and replenishes the body and prepares it for action the next day Consolidates memories
  16. 16. Limitations of Restorative Theories Lack of physical activity does not reduce the amount of sleep neededThe body does not completely “rest” during sleep (REM) as assumed by restorative theories