Sleep Flashcards
(39 cards)
What is sleep?
An altered state of conciouness where we lose control of thoughts, behaviours, sense less stimuli, altered emotional states, unconciously resolving stressors and an altered sense of time
Explain the evolutionary/circadian theory of sleep
Describes how sleep serves as a means to increase an animals chance of survival in their environment
What 3 factors impact an animals sleep needs?
- Food requirements and availability: e.g. Animals who need to eat more sleep less
- Energy conservation: sleeping reduces metabolism conserving energy, animals hibernate over winter when food is scarce
- Safety when asleep: small prey sleep longer to hide, large pray sleep less to escape, large predators sleep longer, diurnal vs. nocturnal
What are 2 criticisms of the evolutionary/circadian theory of sleep?
- Assumes sleep is useful, not essential. Doesn’t explain why all animals must sleep
- Assumes sleep is a way to hide from predators, but it can be dangerous as awareness is reduced
Explain the restorative theory of sleep
Describes how sleep allows us to recharge our bodies, recover from physical & psychological work and grow
What are 3 things organisms need sleep for according to the restorative theory of sleep?
- Physical restoration & growth: body rebuilds and restores itself, cleaning out wastes and releasing growth hormones
- Memory consolidation: REM and slow-wave sleep is important in learning and memory - improves memory of recent learning
- General/mental health: sleep helps to regulate the immune system and neurotransmitters involved in mental health
What are 2 criticisms of the restorative theory of sleep?
- Assumes that sleep is needed to recover, research only shows an increase in sleep after extreme activity eg. a marathon
- Assumes body rests while asleep, but there is an increase in brain activity during REM sleep
Explain the Circadian rhythm
The internal clock in the hypothalamus determines the circadian rhythm. This rhythm influences levels of arousal and hormone secretion altering levels of drowsiness and alertness so we sleep and wake when we need to
What are 4 key factors of the sleep-wake cycle
- Cycle through light and deep sleep stages every 90 minutes
- Deep sleep occurs most in the first few hours of sleep
- REM sleep occurs most in the last few hours of sleep
- High brain activity when awake and alert
4 factors of Stage 1 NREM Sleep
- Transitional state between being awake and falling asleep
- State where images and feelings may flash through the mind causing twitching or a falling feeling
- Heart rate slows, muscles relax, eye movements decrease
- Usually lasts 1-7 minutes
4 factors of Stage 2 NREM Sleep
- Light sleep begins, accounts for about 50% of total sleep
- Reduced reactivity to noise and light
- Heartrate slows further, muscles relax further, eyes stop moving
- Lasts for 10-25 minutes during 1st cycle, increasing throught the night
5 factors of Stage 3 NREM Sleep
- Start of deep sleep, less responsive to stimuli, more difficult to wake
- If woken feel groggy and disorientated
- Important for recovery and growth
- Heart rate reduces further, muscles relax further, eyes don’t move
- Lasts 20-40 minutes
5 factors of Stage 4 NREM Sleep
- Deepest stage of sleep, hard to wake someone
- Dont spend long in the stage before cycling back through to REM sleep
- Important for recovery and growth
- Heart rate is low, muscles are relaxed eyes don’t move
- Lasts 10 - 60 mins
7 factors of REM sleep
- Enter stage after cycling through stages 1 to 4 of NREM sleep
- Low voltage brain waves resemble being awake, but muscles are paralysed
- Vivid dreaming occurs
- Important for memory and learning
- Takes up 25% of sleep cycle
- HR increases, muscles stay relaxed, rapid eye movement occurs
- Lasts 10-60 minutes, increases throughout the night
What is sleep deprivation?
When an individual does not get enough sleep to meet their needs over a period of time
What are 4 causes of sleep deprevation?
- Shift work
- Drugs
- Sleep environment
- Stressors
What is shift work and how does it contribute to sleep deprivation?
- Employment outside the normal period of a working day eg. night shift, requiring people to be active and alert outside their natural circadian rhythm.
- They’re awake when their melatonin levels are high, and adrenalin & cortisol levels are low.
- This continued misalignment of the body’s natural circadian rhythm can lead to shift work disorder (insomnia & chronic sleep dep)
How do drugs contribute to sleep deprevation?
- Depressants induce sleep but impair the sleep cycle reducing the quality of sleep
- Stimulants increase the alertness of the body, making it harder to fall and stay asleep, as well as a longer sleep onset
- Hallucinogens also increase alertness reducing deep sleep, but can also induce sleepiness at inappropriate times
What is sleep environment, and what are the ideal conditions for sleep?
The place where you sleep each night, ideal factors include:
- Temperature: 15-20 degrees (cool)
- Good sleep hygiene (no devices)
- Reduce clutter (Messy room = messy mind)
- Outside light and noise (Dark and quiet)
- Don’t snooze alarm
What are stressors and how do they contribute to sleep deprivation?
Things in your life that cause you stress. High levels of stress prolongs the onset of sleep and disrupts sleep cycles
What is partial sleep deprevation?
Occurs when an individual doesn’t get enough sleep over 1 or several nights
What 4 things can partial sleep deprivation impact?
- Mood
- Reflexes
- Attention
- Vision
How does partial sleep deprivation affect mood?
- Studies show that sleep-deprived people report an increase in negative emotions and a decrease of positive emotions
- Excessive tiredness is often a symptom of mood disorders
How does partial sleep deprivation affect attention?
- Poor sleep reduces attention, as well as learning and processing
- The more sleep-deprived a person is, the less they can pay attention to something
