Chapter 7: Sleep

University:
California State University, Northridge
Course:
PSY 105 | General Psychology
Academic year:

2024
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40
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Sleep and Biological Rhythms Physiological Psychology Circadian Rhythm Sleep Theories of Sleep Circadian cycles Circadian Rhythm A circadian rhythm is the term given to a natural pattern of biological activity with a period of about 24 hours. These patterns are thought to be driven by a circadian clock and have been observed in fungi, plants, and animals. Circadian Rhythm The study of “biological rhythms” has been given the name Chronobiology. These patterns are believed to be partly naturally encoded into each organism but also may be adjusted by external cues such as the presence of sunlight or work demands and schedules….. Rising and setting of the sun provide cues to reset our rhythm but we generate the rhythm ourselves Circadian Rhythm The daily cycle of life, which includes sleeping and waking, is called a circadian (meaning "about a day") rhythm, commonly referred to as the biologic clock. http://www.sleepdisordersguide.com/circadianrhythms.html#ixzz3Wz9f7VCl If we can figure out how biological clocks work, we might be able to treat jet lag, sleep problems, obesity, mental health problems, and other health problems. Circadian Rhythm Circadian Rhythm Timely prediction of seasonal periods of weather conditions, food availability or predator activity is crucial for survival of many species. Although not the only parameter, the changing length of the photoperiod ('day length') is the most predictive environmental cue for the seasonal timing of physiology and behavior, most notably for timing of migration, hibernation and reproduction. Source: Foster, R. & Kreitzman, L. (2005). The Rhythms of Life: The Biological Clocks That Control the Daily Lives of Every Living Thing. London: Profile Books. Ltd. Circadian Rhythm The influence of Circadian rhythms is present in the sleeping and feeding patterns of animals, including human beings. There are also clear patterns of core body temperature, brain wave activity, hormone production, cell regeneration and other biological activities. Circadian Rhythm The influence of Circadian rhythms is present in the sleeping and feeding patterns of animals, including human beings. There are also clear patterns of core body temperature, brain wave activity, hormone production, cell regeneration and other biological activities. Circadian Rhythm Photoperiodism, the physiological reaction of organisms to the length of day or night, is vital to both plants and animals, and the circadian system plays a role in the measurement and interpretation of day length. Circadian Rhythm Sleep Something we will do for about 1/3 of our lives. Sleep Characterized by: 1. reduced or absent consciousness, 2. relatively suspended sensory activity, 3. inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than being in hibernation or a coma. Sleep Coma https://en.wikipedia.org/wiki/Coma Coma is a state of unconsciousness in which a person cannot be awakened; fails to respond normally to painful stimuli, light, or sound; lacks a normal wake-sleep cycle; and does not initiate voluntary actions. • Sleep is an active process that potentially serves some important functions in terms of memory and consciousness. Hence, we can safely say that sleep is far from a state of unconsciousness. • The different stages of sleep undergo constant changes throughout the lifespan. REM sleep has received the most attention and is thought to be of the most functional benefit to humans. • Descriptions of sleep and wake states have focused on psychophysiological measures Sleep Levels Stage I Stage II Stage III (And IV) Non Rapid Eye Movement (NREM) Slow Wave Sleep REM Rapid Eye Movement http://www.youtube.com/watch?v=fNlp0UMqUtM Sleep Levels Awake Characterized by full sensory responsiveness and both Alpha and Beta brain activity SLEEP • Also controlled by the circadian rhythm and mechanisms that keep the body balance. • Several parts of the brain work together to control when you sleep and when you wake up. • Thalamus • Hypothalamus – The suprachiasmatic nucleus (SCN) - the body's biological clock - and the thalamus work together to control slow-wave sleep. • Pons – The management of rapid eye movement (REM) sleep is important Hormones in Sleep • Melatonin – a part of controlling biological rhythms and the immune system • Follicle-stimulating hormone (FSH) – The pituitary gland makes this hormone, which is important for controlling the reproductive system. • Luteinising hormone (LH) – This hormone is made by the pituitary gland and is important for regulating the reproductive system. • Growth hormone – It is made by the pituitary gland and helps the body grow and mature. Sleep Levels Stage I Characterized as a transition stage…between wakefulness and sleep…..Theta activity is present Sleep Levels Stage 2 After about 10 minutes or so, sleep comes……..Theta activity slows and Sleep Spindles begin to appear. Pulse and breathing slower. Slower brain waves Sleep Levels Stage 3 (4) The third level of NREM sleep (formerly called levels 3 & 4) is characterized by slow wave Delta activity. Pulse, breathing and brain activity slower yet. Dominates first half of night REM Sleep Levels Brain electrical activity Muscle activity Eye movement The final stage is REM (rapid eye movement)….Theta/Beta activity increased…muscular paralysis. Eyes move back and forth Dreams more frequent, vivid, complex Brain waves desynchronised Postural muscles most relaxed Durations gets longer toward morning Sleep Levels NREM Slow Wave 60-70 minutes REM 20-30 minutes NREM Slow Wave 60-70 minutes Normal sleep includes Slow Wave NREM and REM cycles of about 90 minutes in duration Why do we have to sleep? • Adaptive evolutionary function – Safety – Energy conservation • Restorative function – Body rejuvenation – growth • Brain plasticity – Enhances synaptic connections – Memory consolidation (strengthen memory) Theories of Sleep • Evolutionary – animals sleep to save energy & avoid danger. • Our eyes aren’t set up to see well at night so when it’s dark, we’re more likely to get hurt. • Sleep is good for the brain and helps it heal. • From a different point of view, sleep is good for your mind (Walker, 2009). - that sleep helps people remember and understand what they learned during the day. • Evolutionary context - Lee Kavanau (2004) has said that you need to sleep because your eyes need time to get more complex - , the brain's two processes compete with each other when you're awake, but when you sleep, one of those processes (vision) has less of an effect on other neural activities, like consolidating memories. Sleep Disorders Sleep Disorders: Sleep Apnea Sleep apnea is a serious sleep disorder that occurs when a person's breathing is interrupted during sleep. People with untreated sleep apnea stop breathing repeatedly during their sleep, sometimes hundreds of times. This means the brain -- and the rest of the body -- may not get enough oxygen. There are two types of sleep apnea: Obstructive sleep apnea (OSA): The more common of the two forms of apnea, it is caused by a blockage of the airway, usually when the soft tissue in the back of the throat collapses during sleep. Central sleep apnea: Unlike OSA, the airway is not blocked, but the brain fails to signal the muscles to breathe due to instability in the respiratory control center. Sleep Disorders Sleep Apnea Sleep apnea can affect anyone at any age, even children. Risk factors for sleep apnea include: Being male, being overweight, being over age 40 Having a large neck size (17 inches or greater in men and 16 inches or greater in women) Having large tonsils, a large tongue, or a small jaw bone Having a family history of sleep apnea Gastroesophageal reflux, or GERD Nasal obstruction due to a deviated septum, allergies, or sinus problems Sleep Disorders Sleep Apnea What Are the Effects of Sleep Apnea? If left untreated, sleep apnea can result in a growing number of health problems, including: High blood pressure Stroke Heart failure, irregular heart beats, and heart attacks Diabetes Depression Worsening of ADHD In addition, untreated sleep apnea may be responsible for poor performance in everyday activities, such as at work and school, motor vehicle crashes, and academic underachievement in children and adolescents. Sleep Disorders Insomnia Insomnia is a sleep disorder that is characterized by difficulty falling and/or staying asleep. People with insomnia have one or more of the following symptoms: Difficulty falling asleep Waking up often during the night and having trouble going back to sleep Waking up too early in the morning Feeling tired upon waking Sleep Disorders Insomnia Types of Insomnia Primary insomnia: Primary insomnia means that a person is having sleep problems that are not directly associated with any other health condition or problem. Secondary insomnia: Secondary insomnia means that a person is having sleep problems because of something else, such as a health condition (like asthma, depression, arthritis, cancer, or heartburn); pain; medication they are taking; or a substance they are using (like alcohol). Sleep Disorders Insomnia Insomnia also varies in how long it lasts and how often it occurs. It can be short-term (acute insomnia) or can last a long time (chronic insomnia). It can also come and go, with periods of time when a person has no sleep problems (episodic insomnia). Acute insomnia can last from one night to a few weeks. Insomnia is called chronic when a person has insomnia at least three nights a week for a month or longer. Episodic insomnia is often associated with periods of life change or situational stress. Sleep Disorders Insomnia Causes of Insomnia Causes of acute insomnia can include: Significant life stress (job loss or change, death of a loved one, divorce, moving) Illness Emotional or physical discomfort Environmental factors like noise, light, or extreme temperatures (hot or cold) that interfere with sleep Some medications (for example those used to treat colds, allergies depression, high blood pressure, and asthma) may interfere with sleep Interferences in normal sleep schedule (jet lag or switching from a day to night shift, for example) Causes of chronic insomnia include: Depression and/or anxiety Chronic stress Pain or discomfort at night Abnormalities of Sleep • Narcolepsy - sudden attacks of extreme sleepiness in the middle of the day – cataplexy (sudden muscle weakness) – can last seconds or minutes. • Others – Sleep talking occurs most commonly in Stage 2 sleep: sleep talkers as if they were carrying on a conversation – Sleep walking tend to occur during Stage 4 sleep: mostly among children, a better idea is to guide the child gently back to bed – Night terrors occur during Stage 3 or Stage 4 sleep (not in REM): causes someone to awaken screaming and sweating with a racing heart rate, sometimes flailing with the arms and pounding the walls • VIDEOs on : insomnia: https://www.youtube.com/watch?v=j5Sl8LyI7k8 sleep apnea: https://www.youtube.com/watch?v=i6lxO6W2-m8 narcolepsy: https://www.youtube.com/watch?v=1PuvXpv0yDM night terror: https://www.youtube.com/watch?v=4Vh56g9b92U