Sleep Flashcards
Three Standard Psychophysiological Measures of Sleep
- sleep lab
- go to peoples home
- measure electrical brain activity via EEG (electroencephalogram)
- measure eye movement during sleep via EOG (electrooculogram)
- measure muscle activity (chin or legs) - useful identifying sleep disorder via EMG (electromyogram)
The three stages of the sleep EEG,
There are two basic types of sleep: rapid eye movement (REM) sleep and non-REM sleep (which has three different stages). Each is linked to specific brain waves and neuronal activity. You cycle through all stages of non-REM and REM sleep several times during a typical night, with increasingly longer, deeper REM periods occurring toward morning.
Stage 1 non-REM sleep is the changeover from wakefulness to sleep. During this short period (lasting several minutes) of relatively light sleep, your heartbeat, breathing, and eye movements slow, and your muscles relax with occasional twitches. Your brain waves begin to slow from their daytime wakefulness patterns.
Stage 2 non-REM sleep is a period of light sleep before you enter deeper sleep. Your heartbeat and breathing slow, and muscles relax even further. Your body temperature drops and eye movements stop. Brain wave activity slows but is marked by brief bursts of electrical activity. You spend more of your repeated sleep cycles in stage 2 sleep than in other sleep stages.
Stage 3 non-REM sleep is the period of deep sleep that you need to feel refreshed in the morning. It occurs in longer periods during the first half of the night. Your heartbeat and breathing slow to their lowest levels during sleep. Your muscles are relaxed and it may be difficult to awaken you. Brain waves become even slower.
REM sleep first occurs about 90 minutes after falling asleep. Your eyes move rapidly from side to side behind closed eyelids. Mixed frequency brain wave activity becomes closer to that seen in wakefulness. Your breathing becomes faster and irregular, and your heart rate and blood pressure increase to near waking levels. Most of your dreaming occurs during REM sleep, although some can also occur in non-REM sleep. Your arm and leg muscles become temporarily paralyzed, which prevents you from acting out your dreams. As you age, you sleep less of your time in REM sleep. Memory consolidation most likely requires both non-REM and REM sleep.
Theories of Sleep
- The essence of recuperation theories of sleep is that being awake disrupts the homeostasis (internal physiological stability) of the body in some way and sleep is required to restore it.
- We sleep to restore energy levels and clear toxins.
- The essence of adaptation theories of sleep is that sleep is not a reaction to the disruptive effects of being awake but the result of an internal 24-hour timing mechanism—that is, we humans are programmed to sleep at night regardless of what happens to us during the day.
Comparative Analysis of Sleep
- Most mammals and birds sleep - which suggests a physiological function
- Is not just a higher-order human function.
- Essential for survival
- No strong relationship between a species sleep time and level of activity, body size or body temperature
Reasons for sleep deprivation
shift work = affects your sleep cycle and can lead to sleep deprivation
sleep disorders
lifestyle - 24/7 society: internet and mobile phones
family commitment - young children
anxiety - increases arousal
stimulants - hinder ability to get to sleep
three predictions that recuperation theories make about the effects of sleep deprivation
- Long periods of wakefulness will produce physiologi-cal and behavioral disturbances.
- These disturbances will grow worse as the sleep de-privation continues.
- After a period of deprivation has ended, much of the missed sleep will be regained.
Signs of sleep deprivation
a whole range of physiological and psychological consequences
- difficulty making simple decisions
- difficulty concentrating
- falling asleep
- weak immune system
- feeling more emotional than usual
- still feeling hungry after eating
Consequences of sleep deprivation
- cognitive function
- emotional wellbeing
- weight management
- reproductive system –> affects testosterone and sperm quality
- immune system
- brain structure affected
- verbal disturbances
- impaired learning, poor decision making, mental fatigue (may be due to abnormal function of prefrontal cortex)
Physiological
- 6-8% decrease in brain metabolic rate
- aching muscles
- headaches
- increase blood pressure
- increase risk of diabetes
- obesity
- seizures
Common themes in the definition of sleep
lack of consciousness/ temporary suspension of consciousness
naturally- occurring state
periodic and recurring
involves mind and body
relaxation and inactivity of muscles
–> sleep presents itself differently in different species, therefore, it is hard to find one definition that is applicable to all animals
Sleep Deprivation Increases the Efficiency of Sleep
- Although people regain only a small proportion of their total lost sleep after a period of sleep depriva-tion, they regain most of their lost slow-wave sleep
- After sleep deprivation, the slow-wave sleep EEG of humans is characterized by an even higher propor-tion of slow waves than usual
- People who sleep 6 hours or less per night normally get as much slow-wave sleep as people who sleep 8 hours or more
- If individuals take a nap in the morning after a full night’s sleep, their naptime EEG shows few slow waves, and the nap does not reduce the duration of the following night’s sleep
- People who reduce their usual sleep time get less NREM 1 and NREM 2 sleep, but the duration of their slow-wave sleep remains about the same as before
- Repeatedly waking individuals during REM sleep produces little increase in the sleepiness they ex-perience the next day, whereas repeatedly wakingindividuals during slow-wave sleep has major ef-fects
REM Sleep
Rapid eye movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream vividly.
Circadian Rhythm
a natural, internal process that regulates the sleep-wake cycle and repeats on each rotation of the Earth roughly every 24 hours. It can refer to any biological process that displays an endogenous, entrainable oscillation of about 24 hours.
zeitgeber
a rhythmically occurring natural phenomenon which acts as a cue in the regulation of the body’s circadian rhythms.
literally “time giver”, i.e., “synchronizer”
Jet Lag and Shift Work
Traveling across time zones can disrupt regular patterns of sleep and wakefulness.
Because the internal circadian alerting system is at its strongest during the daytime, night shift workers often find themselves struggling to sleep “on the wrong side of the clock.”
Good sleep habits (in particular), a regular schedule, and simple workplace measures can help shift workers get the sleep they need.
Symptoms of jet lag may include excessive daytime sleepiness, nighttime insomnia, headache, loss of appetite, gastrointestinal problems, and irritability or mild depression.
The suprachiasmatic nucleus or nuclei (SCN)
is a tiny region of the brain in the hypothalamus, situated directly above the optic chiasm. It is responsible for controlling circadian rhythms. The neuronal and hormonal activities it generates regulate many different body functions in a 24-hour cycle. The mouse SCN contains approximately 20,000 neurons.[1]
The SCN interacts with many other regions of the brain. It contains several cell types and several different peptides (including vasopressin and vasoactive intestinal peptide) and neurotransmitters.