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Sleep Basics. How do scientists study sleep? What are the different stages of sleep? How often do the different sleep stages last and how many times do we cycle through them in a night?
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How do scientists study sleep? • What are the different stages of sleep? • How often do the different sleep stages last and how many times do we cycle through them in a night? • Compared to wakefulness, how do the following physiological processes change during NREM sleep and REM sleep?a) heart rateb) blood pressure c) blood flow to the braind) respiratione) airway resistancef) body temperatureg) sexual arousal • What hormones are released during sleep? • What is the major difference between being asleep and being in a coma or anesthetized?
How do scientists study sleep? • Sleep is a dynamic processinvolving physiological changes in the organs of the body • These changes can be monitored using different techniques: • Electroencephalograms (EEGs) • Electrooculograms (EOGs) • Electromyograms (EMGs)
Electroencephalogram (EOG) • Measures electrical changes in the brain • Electrodes are placed on the scalp in a symmetrical pattern • The electrodes measure small voltages that are caused by synchronized activity in very large numbers of synapses in the brain’s outer layers • The wavy lines of EEGs are called brain waves
Electrooculogram (EOG) • This technique uses electrodes on the skin near the eye to measure changes in voltage as the eye rotates in its socket
Electromyogram (EMG) • This technique measures electrical activity associated with active muscles • Electrodes are placed on the skin overlaying a muscle • In humans, the electrodes are placed under the chin because muscles in this area demonstrate very dramatic changes during the various stages of sleep
How Scientists Study Sleep • EEGs, EOGs, EMGs are recorded simultaneously on continuously moving chart paper or digitized by a computer and displayed on a high resolution monitor • this allows relationships between the three measurements to be seen immediately • The patterns of activity in these three systems provide the basis for classifying the different types of sleep
Stages of Sleep • Sleep is a highly organized sequence of events that follows a regular, cyclic program each night. • The stages of sleep can be categorized into 2 basic stages: • NREM (non rapid eye movement) • REM (rapid eye movement)
NREM Sleep • NREM sleep is divided into 4 stages according to the amplitude and frequency of brain wave activity • Stage 1: regular, low amplitude • Stage 2: sleep spindles • Stage 3 and 4: high amplitude, low frequency waves Note: in stage 4, it is extremely difficult to be awakened by external stimuli
NREM Sleep • Muscle activity in NREM sleep is low, but muscles retain their ability to function • Eye movements normally do not occur during NREM sleep
REM Sleep • REM sleep EEG resembles awake EEGs (low amplitude, high frequency) • Characterized by bursts of rapid eye movements • Movements of eyes may relate to the visual images of dreams • Muscles of the limbs are almost paralyzed resulting in a flat line EMG
Sleep unit: Journal #1 Answers questions 1-3 in your own words
3. How often do the different sleep stages last and how many times do we cycle through them in a night?
Sleep is a cyclical process • During sleep, people experience repeated cycles of NREM and REM sleep beginning with the NREM phase • This cycle lasts aprox. 90- 110 minutes and is repeated 4-6 times per night • As the night progresses, the amount of NREM sleep decreases and the amount of REM sleep increases
The Hypnogram • Periods of NREM and REM sleep alternate throughout the night • The deepest stages of NREM sleep occur in the first part of the night • The episodes of REM sleep are longer as the night progresses
4. Compared to wakefulness, how do the following physiological processes change during NREM sleep and REM sleep?a) heart rateb) blood pressure c) blood flow to the braind) respiratione) airway resistancef) body temperatureg) sexual arousal
Endocrine System- During Sleep • Many hormones are secreted into the blood during sleep: • Growth hormone: related to the tissue repair processes that occur during sleep • Follicle Stimulating Hormone (FSH) and Luteinizing hormone (LH): both involved in maturational and reproductive processes
6. What is the major difference between being asleep and being in a coma or anesthetized?
Sleep vs. Coma and Anesthesia • Individuals in a state of coma or under general anesthesia are not asleep! • They do not exhibit the same brain wave patterns characteristic of true sleep • Their conditions are not reversible: this means that they cannot be awakened by a strong stimulus
Sleep unit: Journal #2 Answers questions 4-6 in your own words
PBS clip: From Zzzz’s to A’s.http://www.pbs.org/wgbh/pages/frontline/shows/teenbrain/view/ 1. How many hours of sleep to you need to get in order to be fully alert? 2. What is the name of your Biological Timing System and how does it change during the teenage years? 3. What analogy does the announcer use for a teen that is trying to function with not enough sleep? 4. What are three daily life functions that sleep affects your ability to do? 5. What is REM sleep and what happens during this time? 6. What is the best predictor of whether or not you will succeed at school? 7. What were the results of the study of the relationship between learning and sleep in teens Charlie and Nicole?
From Zzzz’s to A’s (clip) • How many hours of sleep to you need to get in order to be fully alert? 9 ¼ 2. What is the name of your Biological Timing System and how does it change during the teenage years? The circadian clock: it shifts forwards (in the day) during the teenage years 3. What analogy does the announcer use for a teen that is trying to function with not enough sleep? It’s like a car trying to run on an empty tank. 4. What are three daily life functions that sleep affects your ability to do? Your mood, your ability to think and your ability to perform and react appropriately. 5. What is REM sleep and what happens during this time? Rapid Eye Movement. Dreaming and learning happens during this time. 6. What is the best predictor of whether or not you will succeed at school? Whether or not you get a good night’s sleep. 7. What were the results of the study of the relationship between learning and sleep in teens Charlie and Nicole? Nicole got more REM sleep than did Charlie and she also improved more on the learning tasks than Charlie did. Thus, the more REM sleep you get the better you learn.