SLEEP DP 6-10 Flashcards
Sleep
- ASC marked by reduced metabolism and lowered consciousness
- consists of different stage each distinguished by physiological changes in HR, breathing rate, body temp, muscle tone
Hypnogram - sleep diagram
- graph showing sleep
- sleep in 1.5 hr cycles
- NREM periods decrease throughout the night
- REM periods increase throughout the night
REM
- Stage during the sleep cycle in which electrical brain activity is characterised by beta-wave patterns - high F, low A
- begins about 1.5 hours after falling asleep and returns 4-5 times a night
- EOG - rapid eye movement
- EMG - no muscle movement (atonia - muscle paralysis)
- dream
↑HR, ↑breathing rate, ↑body temp
20% of the night
NREM
- Stages of sleep which where individual is able to move (although usually doesn’t as brain isn’t sending signals to muscles to move) (little dreaming)
- Stages 1 & 2 - awaken easily and may not realise you were sleeping
- Stages 3 & 4 - difficult to wake up, if aroused, will likely be disorientated / confused
-Alpha, theta and delta waves
→ low F, high A - EOG - Slow rolling / no eye movement
- EMG - Little to no movement
- Hypnic jerks + some small movements
↓HR, ↓breathing rate, ↓body temp - Muscles are more relaxed, brainwaves are slow and rhythmical
80% of the night
Biological rhythms
A naturally occurring pattern of cyclic changes in bodily function that repeats itself over time
Circadian rhythms
Biological rhythm that involves changes in bodily functions that occur over a 24hr cycle
eg. daily sleep-wake cycle
Ultradian rhythms
Biological rhythm that involves changes in bodily functions that occur as part of a cycle shorter than 24 hours
eg. NREM/REM cycles of 90 mins within sleep period
Restorative theory
- Sleep replenishes our bodies and minds and allows us to recharge depleted energy resources that have been used up during waking time.
- REM - Replenishes psychological functioning, restores adequate neurotransmitter levels
- NREM - Replenishes physiological functioning, repairs damaged cells and tissues
Detoxifies muscles
Restorative theory - supportive evidence
Most people feel tired before they go to sleep and refreshed and more energetic upon waking (ppl also tend to sleep longer during an illness, suggesting that sleep may help the recovery process)
Restorative theory - limitations
An adequate amount of sleep does not guarantee good health
- Inactive people (such as disabled individuals who are confined to bed) should sleep less than the average active person, but actually experience the same proportions of NREM sleep.
Evolutionary theory
Survival/evolutionary trait
While sleeping, an organism isn’t physically interacting with the environment and is less likely to attract attention of potential predators
Evolutionary theory - supportive evidence
Furthers our understanding of the purpose/function of sleep
Provides a link between the circadian nature of sleep and when we sleep
Evolutionary theory - limitations
- Doesn’t account for the fact that sleep involves a loss of awareness that places individuals in a vulnerable position, as they are not ready to respond to danger if their muscles are in a relaxed state and senses are less attuned to surroundings
- Doesn’t explain our need for sleep, why we must and will eventually sleep, regardless of the environmental circumstance
Newborn
- 16 hrs
- REM 50% NREM 50%
- sleep onset occurs through REM sleep, not NREM stage 1
- each sleep ep only consists of 1-2 cycles
Teenagers
- 9-10 hrs
- REM 20%, NREM 80%
Adults (20-60)
- 8 hrs
- REM 20%, NREM 80%
Elderly
- 5-7 hrs (less deep sleep)
- REM 15%, NREM 85%
- S3-4 NREM sleep disappear, sleep is more fragmented
Sleep wake cycle
- Our bodies are tuned into a 24-hour sleep-wake cycle which is a regular circadian rhythm
- it is determined by an internal biological body clock located in the hypothalamus
- This clock also regulates our level of arousal, metabolism, body temperature + hormone secretions (melatonine)
Circadian phase disorder
Sleep disruption to the internal circadian rhythm due to problems with the timing of the sleep & wake states
- Can be characterised by an inability to fall asleep or remain asleep
Disruption may be caused by:
- Lifestyle, genetics, shift work, jetlag, adolescence etc
Can results in
- Incomina, impairment in social and occupational functioning
Partial sleep deprivation
Is being denied of necessary or desired amounts of sleep
Is having some sleep in a 24hr period but not getting enough to meet your needs in either quantity or quality
What is affected?
- Cognition - logical reasoning and complex thoughts
- Concentration - wandering mind and lack of attention
- Mood - restless and irritable
Symptoms of partial sleep deprivation
Physiological effects
- Drooping eyelids
- Staring and inability to focus the eyes
- Lack of energy
- Fatigue
- slurred speech
- Headaches
Psychological effects
- Affective: emotional
Mood changes, heightened anxiety/depression, irritability, lack of motivation, amplified emotional response
- Behavioural:
Slower reaction times, clumsiness, risk-taking behaviours
- Cognitive: thoughts
Lack of concentration, impaired memory (trouble with encoding, not retrieval), illogical/irrational thoughts, poor decision-making, trouble with simple and monotonous tasks (complex tasks are not affected)
Sleep disorders
The term sleep disorder refers to any problem that disrupts the normal NREM-REM sleep cycle, including the onset of sleep
If sleep phenomena such as dreams and walking/talking during sleep reoccur and disrupt sleep, then this is also considered to be a sleep disorder
Dyssomnias
A problem getting to sleep or staying asleep, or excessive sleepiness (not enough) D = deficiency
Individuals typically experience changes in the amount and/or timing of sleep and how restful it is
Parasomnias
Sleep disorder that involves abnormal movements, sensations, behaviours and dreams while sleeping between stages or falling / waking from sleep affecting the quality of sleep.
Jetlag
A mismatch between an individual’s sleep wake cycle and the day night cycle of their physical environment
Adolescence
A naturally occurring change or malfunction of biological mechanisms or processes regulating the sleep-wake cycle (delayed release of melatonin in adolescence)
Delayed sleep phase syndrome (DSPS)
Teenagers are susceptible to DSPS, which involves an inability to reset the sleep-wake cycle (in response to environmental cues), resulting in a misalignment of the timing of sleep, peak period of alertness, core body temp + hormonal/other daily rhythms.
Ppl with DSPS have difficulty falling asleep + waking up at the desired time
Shift work
A mismatch between an individual’s sleep wake cycle and the sleep wake cycle required for work
Why does delayed sleep onset occur?
Melatonin is a hormone that helps to induce sleep. During adolescent the release of this hormone is delayed for up to 2 hours
Dyssomnia - Sleep-onset insomnia
Sleep disorder involving persistent difficulty falling asleep at the usual sleep time impacting quality of sleep
Parasomnia - Sleep walking
- Sleepwalking (somnambulism) involves walking/performing other behaviours whilst asleep and sometimes conduct routine activities (dressing/cleaning)
- A sleepwalking episode may involve activities that vary in degree of complexity and duration (may be calm, moderate or vigorous)
- Sleepwalkers eyes are usually open but their eyes have a ‘blank stare’
- The sleepwalker is typically unresponsive to any attempt to communicate
- Occurs in stage 3 or 4 of NREM sleep (deep sleep) and can go for up to half an hour (usually between 5-15 mins)
Impact of delayed sleep onset
- Delayed sleep onset increases the susceptibility of adolescents to a sleep phase syndrome (inability to reset their sleep-wake cycle in response to environmental cues)
- Resulting in a misalignment of the timing of sleep, peak period of alertness, core body temp and hormonal and other daily rhythms relative to societal norms.
- It can create a vicious cycle resulting in a circadian phase disorder which causes extreme difficulty falling asleep and sleepiness when waking in the morning
→ This is because many adolescents try to compensate for their lost sleep, by sleeping approx 2hrs longer on weekends, perpetuating the disorder and disrupting the normal sleep cycle
Treatment of circadian phase disorder
Bright light therapy
Cognitive Behavioural Therapy (CBT)
Bright light therapy
- Light is the strongest agent for synchronising circadian rhythms and timed exposure to bright light is often used in the treatment of circadian phase disorders
- Light therapy can be used to reset the body’s internal clock
During light therapy, your eyes are exposed to intense but safe amounts of light for a specific and regular length of time as artificial light may be used to affect the body clock in the same way that sunlight does
Cognitive Behavioural Therapy (CBT)
- CBT involves substituting thoughts, behaviours and habits that inhibit sleep and replacing them with those that promote good sleep
- People with insomnia develop sleep-related thoughts/behaviours that have the unintended consequence of maintaining/worsening their sleep problems
These may include: - Misunderstandings about the causes of insomnia
- Faulty beliefs about sleep-promoting practices
- Daytime napping or spending a lot more time in bed
- These inappropriate thoughts/behaviours can lead to excessive worry about not sleeping
Suprachiasmatic nucleus
The suprachiasmatic nucleus is triggered by the presence of light and adjusts our sleep–wake cycle accordingly. It sends neuronal messages to the nearby pineal gland to secrete more or less melatonin into the blood.
- Less light - the SCN signals the pineal gland to produce and secrete more melatonin
- When the SCN detects light in the morning, it inhibits the release of melatonin.
