6. Sleep Flashcards
Define sleep
A circadian state characterised by partial or total suspension of consciousness, voluntary muscle inhibition, and relative insensitivity to stimulation.
Why did early humans become motivated to sleep during the night
Evolutionary theory
There was a greater risk of injury while looking for food and drink when it was dark, as well as risk of predators that would threaten survival. Sleeping allowed for energy to be conserved.
Hunting and seeking water are better carried out in the daytime.
Impact of transition from sleeping on trees to on the ground
Evolutionary theory
Allowed for deeper and longer sleep. Scientists believe this improved sleep quality, led to enhanced brain function, and less sleep time required.
Meaning there was more time for learning and socialising.
Restorative theory of sleep
Restorative theory of sleep claims that sleep allows humans to recharge their bodies, to grow, and recover from the physical and psychological work encountered during the day.
Specific processes that occur during sleep
Restorative theory of sleep
- Cells resupply and stock up energy levels.
- Heal injuries.
- Reorganising and categorising memories and learned information.
Criticisms of restorative theory
- Assumes more sleep is required when physically active.
- Assumes body rests during sleep when brain is active.
Sleep-wake cycle
The reoccurring pattern of wakefulness and sleep that individuals undergo daily.
Melatonin
Sleep-wake cycle
The hormone that regulates the sleep wake cycle.
Circadian rhythm
The bodily cycle that lasts around 24 hours and controls the nocturnal release of hormones including melatonin.
Number and duration of sleep cycles
Sleep-wake cycle
4-6 sleep cycles with each cycle lasting about 90 minutes.
NREM stage 1
Description, duration, eyes, and muscles
Transitional period between wakefulness and sleep. Lasts 5-10 minutes. Eyes are closed but easy to wake, slow rolling movement until asleep. Muscles begin to relax.
NREM stage 2
Description, duration, eyes, muscles, body temperature, and heart rate
Light sleep. Lasts 20-25 minutes the first cycle, increasing with each repetition. Eye movement stops. Muscles continue to relax with occaisional twitches. Body temperature drops. Heart rate slows.
NREM stage 3
Description, duration, eyes, muscles, body temperature, and heart rate
Deep sleep stage, harder to rouse, disoriented if woken. Lasts 20-40 minutes for the first few cycles, decreasing later. Minimal eye movement. Muscles are most relaxed. Body temperature and heart rate decrease.
What happens in NREM stage 3
During this stage the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system.
REM
Description, duration, eyes, muscles, body temperature, and heart rate
More active brain, dreams. Lasts 10-60 minutes, increasing with each repetition. Eyes move rapidly in many directions, don’t send any visual information. Muscles temporarily paralysed. Heart rate may match awake rate.
Significance of REM sleep in regards to mood and memory
Dreams, which mostly occur during REM, may be involved in processing emotions. Brain processes learned information and motor skills from the day, committing some to memory and deleting some.
Wakefulness preparation in REM stage
CNS activates, which may assist in waking up. May explain why we spend more time in REM as the night progresses and why we wake easily during this stage.
Define sleep deprivation
The condition of getting inadequate quantity or quality of sleep.
Shift work
Causes of sleep deprivation
Night shift work disrupts natural circadian rhythms leading to challenges in aligning sleep-wake cycles with various melatonin, adrenaline, and cortisol levels.
Sleeping during the day can be interrupted by environmental factors such as light and noise.
Drugs
Causes of sleep deprivation
- Stimulants can hinder sleep by stimulating CNS.
- Alcohol is a depressant which can disrupt sleep once it wears off, causing people to wake up.
- Certain prescribed medicines can induce insomnia or impact sleep stage progression.
Stress
Causes of sleep deprivation
Stressors can hinder falling asleep and staying asleep due to feelings of anxiety and worry instead of relaxation. E.g. family, school, or work difficulties, major illness, death of a loved one.
Environmental factors
Causes of sleep deprivation
Can impact the ability to sleep well, such as temperature, noise, snoring, bright light, and electronic distractions.
Define partial sleep deprivation
Occurs due to a short-term lack of sleep over a 24-hour period of up to a few consecutive nights. E.g. sleeping less than 5 hours over a 24-hour period.
Potential causes of partial sleep deprivation
Staying up late to complete something by a deadline, jet lag, stress making it difficult to fall asleep, illness, partying.
Reflex speed
Physiological effects of partial sleep deprivation
Decreased or slower reflex speed, it takes longer to react to stimuli.
Vision
Physiological effects of partial sleep deprivation
Vision may be blurry, may experience increased sensitivity of light, eyes may become dry and twitch.
Mood
Psychological effects of partial sleep deprivation
Decreased positive mood, increased negative mood, difficulty regulating mood, and increase irritability.
Attention
Psychological effects of partial sleep deprivation
Shorter attention span, lapses in attention, and impaired selective attention.
Define chronic sleep deprivation
When an individual routinely sleeps less than the time required for optimum functioning.
Potential causes of chronic sleep deprivation
Insomnia, chronic pain or illness, caring for a baby, and long work hours.
Heart disease
Physiological effects of chronic sleep deprivation
Strong association with increased risk of cardiovascular problems such as high blood pressure, coronary heart disease, heart attack, and strokes.
Obesity
Physiological effects of chronic sleep deprivation
Inadequate sleep is linked to increase calorie and carbohydrate consumption, contributing to obesity.
Insomnia
Psychological effects of chronic sleep deprivation
Increasing difficulty falling asleep or staying asleep. Common for insomniacs to wake up not feeling rested.
Anxiety
Psychological effects of chronic sleep deprivation
Poor sleep strongly associated with conditions such as depression and anxiety. Emotional regulation is negatively affected by chronic sleep deprivation, which can exacerbate symptoms of anxiety.
Define sleep hygiene
The set of behavioural and environmental aspects that support healthy sleep patterns.
Management of electronic devices
Techniques to improve sleep hygiene
Don’t use electronic devices such as TV’s, smartphones, tablets, and computers at least 30 minutes before bedtime. This gives melatonin levels time to rise.
Consistent sleep patterns
Techniques to improve sleep hygiene
Having a consistent sleep pattern helps in regulating the circadian rhythm.
Behaviours that help with consistent sleep patterns
Techniques to improve sleep hygiene
- Setting a bedtime that allows for the recommended amount of sleep according to age.
- Avoid caffeine, alcohol, and heavy meals before bedtime.
- Avoid vigorous exercise 2 hours before bedtime.
Creation of a healthy sleep environment
Techniques to improve sleep hygiene
Circadian rhythms can change due to an uncomfortable sleeping space.
What does creation of a healthy sleep environment involve
Techniques to improve sleep hygiene
- Keeping the bedroom free of distractions, technology, and unnecessary noise.
- Comfortable and cool temperature
- Adequate darkness
How do electronic devices impact melatonin production
The blue light emitted from electronic devices inhibits the production of melatonin, which disrupts the circadian rhythm, making it difficult to fall asleep.
Importance of avoiding daytime napping
Napping during the day can lead to not feeling tired or being able to fall asleep at your regular bedtime, which will lead to an inconsistent time going to sleep.
How does a dedicated sleep space impact sleep
Only using your bed for sleep helps create a cognitive link between your bed and sleep, allowing you to become relaxed and feel ready for sleep when you go to bed.
E.g. not reading, going on electronic devices etc.
Aim of He et al.’s study
The study aimed to assess the effects of restricting mobile phone use before bedtime on sleep, pre-sleep arousal, mood, and working memory.
Sampling and allocation method of He et al.’s study
- Participants were recruited with a convenience sampling method.
- 38 participants were randomly allocated to a intervention group or a control group.
Sample refinement procedure of He et al.’s study
Exlusion criteria
To avoid any participant extraneous variables.
* Self-reported medical conditions such as depression or schizophrenia.
* Use of medication, devices, or hypnotics to assist sleep.
Data collection tool for He et al.’s study
Sleep quality meausure (subjective sleep quality, sleep latency, sleep duration etc.), sleep diary, arousal measure (PSAS), mood measure, and working memory.
Baseline data was collected before intervention.
Method of He et al’s study
- Participants in intervention group were instructed to refrain from using their mobile phone for 30 minutes before bedtime.
- Participants in control group didn’t receive any instructions.
Findings of He et al.’s study
Sleep latency, sleep duration, sleep quality, pre-sleep arousal
Restricting mobile phone use before bedtime was effective in reducing sleep latency and pre-sleep arousal, increasing sleep duration, improving sleep quality.
Findings of He et al.’s study
Affect and working memory
Positive affect increase, negative affect decreased, and working memory improved.
Contributions of He et al.’s study
Demonstrates that the simple intervention of restricting mobile phone use before bedtime positively affects various aspects of sleep.
Limitations of He et al’s study
- Use of sleep diary and PSQI to measure participants’ sleep, which may not be very objective.
- Small sample size limits generalisability.
