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Characteristics and Patterns of Sleep

Unit 3 Psychology RAH. Characteristics and Patterns of Sleep. N REM Sleep (non rapid eye movement sleep) REM Sleep (rapid eye movement sleep) These occur in continuous cycles, with one following the other.

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Characteristics and Patterns of Sleep

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  1. Unit 3 Psychology RAH Characteristics and Patterns of Sleep

  2. NREM Sleep (non rapid eye movement sleep) • REM Sleep (rapid eye movement sleep) • These occur in continuous cycles, with one following the other. • In adults, one cycle of NREM sleep last for about 70 to 90 and consists of 4 distinct stages (identified by different brain wave patterns). • REM follows each period of NREM sleep. • A complete sleep cycle last for about 80 to 120 minutes and we repeat if 4 or 5 times during 8 hours of sleep. Types of Sleep

  3. NREM Sleep • Approx 80% of our sleep time is NREM. • Brain active during NREM • Believed that it is the time when the body recovers: • Repairing body tissue • Removing waste products • Replenishing neurotransmitters • E.g. Increase in deep sleep experienced in NREM after vigorous exercise. • NREM consists of 4 stages from light sleep to the stage of deepest sleep and back to light sleep. • Every stage is dominated by a particular brain wave pattern. • Frequency • Number of brain waves • Amplitude • Intensity of brain wave

  4. Hypnogogic State • Transition period from being awake to being asleep. • May last a minute or 2. • People may experience: • Flashes of light or colour • Floating or weightlessness • Dreamlike images • Swift jerky movements • Sense of falling or slipping

  5. NREM – Stage 1 • Occurs as we drift into and out of a true sleep state. • Physiological changes: • Decrease in heart rate • Respiration • Body temp • Muscle tension • Hypnic Jerk: muscles relaxing can result in ‘jerking’ (spasm). • Decrease in alpha waves and replaced by theta waves. • Lasts for about 5-10 minutes.

  6. NREM – Stage 2 • Light stage of sleep. • Point where you are truly asleep. • Easily awakened. • Lasts approx 20 mins. • Body movements lessen. • Temp continues to fall. • Heart rate slower. • Mainly theta waves. • Sleep spindles: • Brief bursts of higher frequency of brain wave activity. • An indicator that a person is truly asleep. • Brain still responds to various external and internal stimuli, e.g. someone entering the room. • This stage is still considered to be light.

  7. NREM – Stage 3 • Start of deepest period of sleep. • Referred to as moderately deep sleep. • Heart rate, blood pressure and body temp continue to drop, breathing continues to be slow and steady. • Relaxed and less responsive. • Delta waves begin to appear. • Slow large, regular, brain waves. • Slow waves sleep (SWS). • Generally begins ½ hour into sleep. • When EEG recordings show that delta waves comprise more than 50% of the brain wave activity, the person has entered stage 4.

  8. NREM – Stage 4 • Deepest stage of sleep. • Very deep sleep. • Muscles completely relaxed. • Delta waves dominate. • Difficult to wake person. • Sleep inertia – post awakening mental lag. • 1st cycle – 20mins. • As night progresses, less and less time is spent in stages 3&4. • Sleep walking, sleep talking and night terrors (and bedwetting) occur.

  9. NREM Cycle Conclusion • NREM cycle from stage 1-4 takes about 45-60 minutes. • We then move progressively up through stages 3,2 and 1. • Our brain and body respond as if we are at the point of waking up. • These are signs of moving into REM.

  10. REM sleep • Period of Rapid Eye Movement sleep during which the eyeballs rapidly move beneath the closed eyelids. • Brain wave pattern is irregular. • Low amp/high frequency beta waves. • REM considered to be deep sleep, as people are difficult to wake during this period.

  11. REM Sleep – Physiological changes • Internal functioning more active during REM the during NREM. • Heart faster and more irregular. • Blood pressure rises. • Breathing faster and more irregular. • Yet, sleeper is totally relaxed. • Also called paradoxical sleep – internally, the brain and body are active, yet body appears calm and inactive.

  12. REM sleep - Dreaming • Most dreaming occurs during REM. • Research suggest we dream several times a night. • Specific movements for eye movements is unclear. • It’s believe to be related to physiological activity that is occurring at the same time as random, neural activity of the brain. • Purpose of REM unclear. • Some research suggests that REM assists in consolidating of embedding new memories in the brain by strengthening newly formed neural connections. • General agreement that REM probably serves some biological need. • Throughout the night, we pass continuously through NREM and REM sleep cycles, with REM periods lengthening and occurring closer together as the night progresses.

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