By Manpreet Basi MD 1 Case Study 340 Electroencephalogram EEG Electrodes placed on the scalp to provide a gross record of the electrical activity of the brain Scientists use EEG to measure electrical brain activity during the five stages of sleep When you fall asleep you pass through s ID: 440281
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Slide1
Sleeping and Dreaming
By: Manpreet Basi
MD 1 Case Study
340Slide2
Electroencephalogram
(EEG):
Electrodes placed on the scalp to provide a gross record of the electrical activity of the brainSlide3
Scientists use EEG to measure electrical brain activity during the five stages of sleep. When you fall asleep, you pass through stages 1 to 4 (the deepest level of sleep) as your brain becomes less active. You then go through the stages in reverse before 5 to 15 minutes of stage 5: rapid eye movement (REM) sleep. During REM sleep, your eyes dart about, your brain is frantically active and you dream. The whole cycle lasts about 90 minutes and repeats throughout the night.Slide4
EEG Waves of Wakefulness:
Awake, but Non-Attentive –
Large, Regular Alpha waves
Awake and Attentive –
Low amplitude Fast Irregular Beta
waves
Slide5
Stages of Sleep:
Sleep stage 1 – brief transition stage when first falling asleep
Stages 2 through 4 (slow-wave sleep) - successively deeper stages of sleep
Characterized by an increasing percentage of slow, irregular, high-amplitude delta waves Slide6
Stages of Sleep:
Upon reaching stage 4 and after about 80 to 100 minutes of total sleep time, sleep lightens and returns to stages 3 and 2
REM sleep emerges, characterized by EEG patterns that resemble beta waves of alert wakefulness
muscles most relaxed
rapid eye movements occur
dreams occur
Four or five sleep cycles occur in a typical night’s sleep - less time is spent in slow-wave,
more is spent in REMSlide7Slide8
Functions of Sleep:
Restoration Theory – Body wears out during the day and sleep is necessary to put it back in shape
Preservation and Protection Theory -
To
preserve energy and protect during the time of day when there is little value and considerable dangerSlide9
Circadian rhythm:
Any rhythmic change that continues at close to a 24-hour cycle in the absence of 24-hour cues:
Body Temperature
Cortisol
Secretion
Sleep and Wakefulness
In the absence of time cues, the cycle period will become somewhat longer than 24 hoursSlide10
Sleep Deprivation:
Has little effect on performance of tasks requiring physical skill or intellectual judgment
Hurts performance on simple, boring tasks more than challenging ones
Long periods of sleeplessness can cause paranoia and hallucinations at the time, but occasional sleep deprivation doesn't do any long-term damage.
Robert McDonald broke the world record in 1988 when he stayed awake for over 18 days. Slide11
Individual Differences in Sleep Drive:
Some individuals need more and some less than the typical 8 hours per night
Nonsomniacs
- sleep less than most people and do not feel tired during the day
Insomniacs - people that have a normal desire for sleep, but are unable to and feel tired during the daySlide12
Sleep Disorders:
Somnambulism - Sleepwalking
Nightmares - frightening dreams that wake a sleeper from REM
Night terrors - sudden awakening from sleep and intense fear accompanied by physiological reactions (e.g., rapid heart rate, sweating) that occur during slow-wave sleep
Narcolepsy - overpowering urge to fall asleep that may occur while talking or standing up
Sleep apnea - failure to breathe when asleepSlide13
How much sleep is needed:
As a person grows older, less sleep is needed. For example a baby needs 16hrs of sleep where as an adult needs 7 hrs of sleep.Slide14
Dreams and REM Sleep:
Everyone dreams several times a night
True dream - vivid, detailed dreams consisting of sensory and motor sensations experienced during REM
Sleep thought - lacks vivid sensory and motor sensations, is more similar to daytime thinking, and occurs during slow-wave sleepSlide15
Why do we dream:
Researches till this day are not sure why.
Some think it is a key to our subconscious or
their purpose may be to keep us asleep - the brain's natural entertainer, or it is a way for our brain to be deleting unnecessary information and retaining important information to be stored in our memory.Slide16
Brain Mechanisms Controlling Sleep:
Sleep is promoted by a complex set of neural and chemical mechanisms
Daily rhythm of sleep and awakening
Suprachiasmatic nucleus of the Hypothalamus
Pineal gland’s secretion of Melatonin
Slow-wave sleep
Raphe nuclei of the medulla and Pons and the secretion of Serotonin
REM sleep
Neurons of the PonsSlide17
Thank you Slide18
http://library.wellcome.ac.uk/doc_WTX042113.html
http://psychcentral.com/disorders/sleep/rem.htm