Sleep, Psychology, Unit 4
Zeitgeber
'Time giver' - Environmental time cues that help to maintain the biological clock to a 24- hour day.
Hypothalamus- supracharismatic nucleus
Master biological clock that regulates the timing and the activity of the sleep-wake cycle. Receives information of the incoming light from the eyes to adjust cycle. Sends message to nearby pineal gland to secrete more or less of the hormone melatonin.
Physiological causes of insomnia
Medical problems, severe or persistent pain, excessive use of alcohol or other drugs that disrupt the sleep cycle
Partial sleep deprivation
Partial sleep deprivation is having some sleep in a 24 hour period but not getting enough to meet your needs in either quantity or quality
lifestyle factors
Shiftwork, stressful or low stress job, active or inactive lifestyle, diet and health,
Genetics
Studies found identical twins have more similar sleep patterns then fraternal twins Females tend to need more sleep than males
Slow Wave Sleep
The presence of delta waves is used by researchers to define the beginning of slow wave sleep (SWS), so called because of the slower frequency delta waves
Travelling from NREM stages 1-4
The progression through the first NREM sleep cycle from stage 1 to stage 4 takes about 45 to 60 minutes or so before we gradually move back up through stages 3 and 2. Having passed through one complete NREM sleep cycle, we are unlikely to awaken, although our brain and body begin to respond as if we are on the point of waking. These are signs that we are about to move into REM sleep.
R.E.M 'sub-states'
Tonic REM and phasic REM, which are more similar to each other than to any of the NREM stages. However, the tonic-phasic distinction is primarily made for certain research purposes only. REM sleep usually is not divided into stages
Total Sleep Deprivation
Total sleep deprivation is going without sleep for a 24 hour period, for one night or several nights in a row
Diurnal rhythms
When a circadian rhythm is synchronised with a day-night cycle
circadian rhythm
a cycle of bodily rhythm that occurs over a 24-hour period
Physiological changes that indicate a lower level of bodily arousal.
a decrease in heart rate, respiration, body temperature and muscle tension — are all evident in stage 1. Some slow, rolling eye movements may also be observed.
Narcolepsy
a sleep disorder characterized by uncontrollable sleep attacks, straight into a period of REM sleep. Cataplexy: complete loss of muscle tone which cause the individual to relax. Vivid and frightening dreams Short period of paralysis after waking up
Microsleeps
brief sidesteps into sleep lasting only a few seconds after 3-4 days of sleep deprivation. Person appears to be awake EEG pattern resembles stage 1-2 NREM
entrainment
the process of altering the free running cycle to fit a different rhythm
sleep latency
the time it takes from being awake to being asleep
sleep onset (hypnagogic state)
the transition from being awake to being asleep, primarily characterised by the slowing, reduction and eventual disappearance of alpha brain activity.
sleep deprivation psychosis
A few days without sleep can lead to sleep deprivation psychosis, resulting in depersonalisation (loss of personal identity) and difficulty coping. Depression, anxiety, hypertension, obesity, diabetes and more. Causes temporary effects which reverse after sleeping.
biological rhythms
natural cycles of activity that the body must go through
Posture movements in a typical nights sleep
-According to Hobson (1988), everybody makes at least eight to 12 major posture shifts in a typical night's sleep. Poor sleepers may even double or triple this figure. Most people change their sleeping position twice per cycle. The first change usually occurs at the end of NREM stage 4 sleep, and the next major movement occurs just before commencing REM sleep.
Is REM the lightest stage of sleep?
-REM sleep is clearly more like wakefulness than NREM sleep when brain wave activity is considered. However, if muscle tone is considered, then REM sleep can be called deep sleep due to muscle tone being at its lowest point. Therefore, psychologists tend to view REM sleep as sharing properties of both light and deep sleep.
NREM Stage 3
-Stage 3 is the start of the deepest period of sleep. It has been described as moderately deep sleep. -Transitionary stage between the shallow sleep of stage 2 and the deep sleep of stage 4. -Stage 3 typically lasts only a few minutes, sometimes up to 10 minutes, and constitutes about 3 to 8% of total sleep time. In sleep cycles in the latter half or so of a sleep episode there may be no stage 3 sleep at all -In this stage, people are difficult to arouse, but if they are awoken they are often groggy and disoriented. The arousal threshold is higher than for stage 2. EEG activity is also noticeably different from that of earlier NREM stages. Brain waves slow further, with delta waves becoming increasingly prominent and making up about 20-50% of the brain wave pattern recorded during the stage.
NREM Stage 4
-Stage 4 is the deepest stage of sleep with the highest arousal threshold. It might best be called very deep sleep. -Delta waves dominate the EEG pattern. They occur more than 50% of the time (which defines the commencement of the stage) and may become even slower and larger than those in stage 3. - It is at this point during a sleep episode that people are often said to be 'sleeping like a log' or 'out like a light'. When they are woken, they can feel groggy and take several minutes to orient themselves, and usually have a poor memory of sleep events. SLEEP INERTIA- Post-awakening mental lag. -In the first sleep cycle, a person may spend between 20 to 40 minutes in stage 4, after which a series of body movements usually marks the transition to lighter non-REM sleep stages. A brief, 1- or 2-minute period of stage 3 sleep might occur, followed by perhaps 5 to 10 minutes of stage 2 sleep interrupted by body movements preceding the initial REM period. -Overall, stage 4 makes up about 10 to 15% of total sleep time
insomnia (n)
A problem which involves continually getting insufficient sleep.
Sleep Apnoea
A temporary suspension of breathing for short periods during sleep 30secs-2 minutes
Psychological effects of sleep deprivation
Affective (emotional): Mood changes, heightened anxiety/depression, irritability, and lack of motivation. Behavioural: Slower reaction times, clumsiness, and risk-taking behaviours. Cognitive: Lack of concentration, impaired memory (trouble with encoding, not retrieval), illogical/irrational thoughts, poor decision-making, and trouble with simple, monotonous tasks.
Sleep Disorders
Any problem that disrupts the normal NREM-R.E.M sleep cycle, including the onset of sleep.
Rapid Eye Movement (REM)
Approximately 20-25% of our total sleep is spent in REM sleep. REM sleep is defined as spontanous bursts of rapid eye movements by which the eyeballs move quickly behind closed eyelids. - The body's internal functioning is more active during REM sleep than during NREM sleep. The heart rate is faster and more irregular. Blood pressure rises, and breathing is quicker and more irregular. However, the sleeper looks totally relaxed. -REM sleep is called paradoxical sleep — internally, the brain and body are active, while, externally, the body appears calm and inactive. The purpose of the apparent body paralysis remains unclear. -Most likely to dream- storyline: from realistic to total fantasy -The first REM period that occurs earlier in the night may last for only 1 to 5 minutes or so, the second about 12-15 minutes, the third about 20-25 minutes, while a later REM period towards the end of a sleep episode may last even longer. -The arousal threshold of REM sleep throughout the night is variable. It seems to depend on when during a REM period awakening is attempted. Generally, the arousal threshold may be like that of NREM stage 2 or NREM stage 4
Total Sleep Deprivation
Can have detrimental effects on the body both physically and psychologically and is theorised to potentially lead to death Case study- DJ Peter Tripp: The secrets of sleep (1959), 8 days without sleep Non-human studies: sleep deprived rats were unable to maintain a constant body temperature and eventually died after 2-3 weeks of no sleep. Autopsies shows that their immune systems collapsed, resulting in blood poisoning and death
Ultradian rhythm
Changes in bodily functions that occur as a part of a cycle less than 24 hours. -e.g heartbeat (thousands of times/24 hours), respiration, sleep, eating cycle
Circadian phase disorders
Characterised by an inability to fall asleep or remain asleep Lifestyle factors Genetics Shift work Jet lag Adolescence Can result in: Insomnia Impairment in social and occupational functioning
Treating insomnia
Cognitive behavioural therapy (CBT) Substituting unwanted thoughts and behaviours with more desirable ones. Substituting thoughts, behaviours and habits that inhibit sleep and replace with those that promote sleep
Sleep terrors
Sleep terrors tend to occur during the deep sleep of stages 3 and 4. A person experiencing a sleep terror may awaken suddenly, 'terrified' and perspiring profusely. Unlike the experience of a nightmare, a person has little or no recall of their sleep terror episode on awakening.
sleep apnea
Disorder marked by interruptions of breathing during sleep
Sleep phenomena
Dreams and walking and talking during sleep disrupt sleep is a sleep disorder
NREM-deprivation
During states 3-4 growth hormones are released and this assists in the growth and repair of the body A loss of NREM may prevent restoration of the body and its ability to replenish energy supplies
Psychological causes of insomnia
Emotional or social disturbances- relationship problems, the death or serious illness of someone close, upcoming important events or major lifestyle changes
Physiological effects of sleep deprivation
Fatigue, trembling hands, dropping eyelids, staring and inability to focus the eyes, slurred speech, lack of energy, increased pain sensitivity, headaches Impaired immune system, heart rate variability, risk of heart disease
Treatment or narcolepsy
Hypocreten substitutes
Sleepwalking (somnambulism)
Involves walking whilst asleep and sometimes conducting routine activities Stage 3 or four of NREM sleep between 5-15 minutes
REM-deprivation
Loss of motor coordination Poor concentration Poor memory Irritability A tendency to hallucinate R.E.M. rebound Restoration theory
Hormones involved with sleep
Melatonin, adenosine
Restorative theory (recovery theory)
Sleep provides a time out to help us recover from depleting activitives during waking time that use up the body's physical and mental resources.
NREM Stage 1
NREM stage 1 is the entry point of sleep for most people (but in infancy and certain sleep disorders such as narcolepsy, sleep onset may occur into REM sleep). -NREM stage 1 occurs as we drift into and out of a true sleep state. We tend to gradually lose awareness of ourselves and our surroundings, but some of the time we may be aware of faint sounds in our environment. -Lasts about 5 minutes after falling asleep (4/5% total sleep time) -Low arousal threshold- wake up feeling like we haven't slept at all. Can be awoken by a simple nudge. -A common sign of severely disrupted sleep is an increase in the amount and percentage of stage 1 sleep
NREM Stage 2
NREM stage 2 is a period of light sleep, and during the first cycle some researchers identify this as the point at which someone can be said to be truly asleep. -Higher arousal threshold than Stage 1 -About midway through stage 2, we are unlikely to respond to anything except extremely strong or loud stimuli, indicating that our sleep has become noticeably deeper. -Stage 2 in the first cycle lasts for about 10 to 25 minutes and lengthens with each successive cycle, eventually constituting about 45 to 55% of the total sleep episode, which is the bulk of an 'average' person's sleep each night. -Brief bursts of rapid brain waves (called sleep spindles), lasting for about 1 or 2 seconds periodically appear, and their presence is used as an indicator by most researchers that the person is truly asleep.
Sleep-wake cycle
Our bodies are turned into a 24 hour sleep-wake cycle which is a regular circadian rhythm Internal clock in the hypothalamus This clock also regulates our level of arousal, metabolism, body temperature and hormone secretions
Dysomnias
Problems getting to sleep or staying asleep, or excessive sleepiness DEFICIENCY
Juergen Aschoff- The sleep-wake cycle in a time free environment
Refer to textbook - section 9.1
NREM sleep (restorative)
Restoring and repairing the body
REM sleep (restorative)
Restoring and repairing the mind Role in procedural (motor skills) and implicit (without awareness) memories.
Adolescence
Shifts towards evening (phase delay) Delayed sleep onset - Melatonin is a hormone that helps to induce sleep. During adolescence the release of this hormone is delayed for up to 2 hours. Melatonin release is controlled by circadian rhythms but can also be effected by light It is also thought social factors can impact (e.g. Homework demands, after school activities, internet).
Sleep as an ultradian rhythm
Sleep cycle generally lasts 90 minutes.
sleep deprivation
Sleep deprivation is any significant loss of sleep, resulting in problems in concentration and irritability
Parasomnias
Sleep disorders that involve abnormal movement, emotion, perceptions, behaviour and dreams while asleep, between stages of falling or waking from sleep. PERPLEXING
General statements about the pattern of sleep:
Sleep is entered through NREM sleep. NREM sleep and REM sleep alternate with a period near 90 minutes. NREM stages 3 and 4 (SWS) predominates in the first third of the night. REM sleep predominates in the last third of the night. Wakefulness in sleep usually accounts for less than 5% of the night. NREM stage 1 sleep generally constitutes approximately 2% to 5% of sleep. NREM stage 2 sleep generally constitutes approximately 45% to 55% of sleep. NREM stage 3 sleep generally constitutes approximately 3% to 8% of sleep. NREM stage 4 sleep generally constitutes approximately 10% to 15% of sleep. NREM sleep, therefore, is usually 75% to 80% of sleep. REM sleep is usually 20% to 25% of sleep, occurring in four to six discrete episodes.
Evolutionary theory (circadian theory)
Sleep is used to enhance our survival. We use sleep as a way of protecting ourselves. Relationship of sleep to circadian rhythms. -conserving energy, hidden and protected from predators after eating, drinking, caring for young.
