somnul 2 Flashcards
what do we mean by enough sleep
there are individual differences when it comes to sleep requirements
newborn babies need 14-17h sleep
recommended amount of sleep decreases through the life course
adults: 7-9h
what are the individual differences
some people can function on less sleep than hours
when people sleep very long or very short, could be a sign of health problems
you may be sleep deprived, if you can’t wake up when alarm goes off, and know that you are not functioning to the best of your ability
major effects of total sleep deprivation
scientists looked at effects of total sleep deprivation in rats
rats were put on a rotating disk
if they stopped moving, they would be pushed and thrown in to water
there was wight loss
skin became problematic
problems with regulating temperature
in 2-3w they died
fatal familial insomnia FFI
a rare genetic disease
ppl miss out on sleep and die within an average of 18m
abnormal proteins build up in the brain
attacks the thalamus which is important in sleep-wale cycles
results in reduction in sleep length and deterioration of sleep stages
does the sleeplessness lead to death in FFI
symptoms of FFI include dementia, problems speaking and swallowing
it’s not insomnia that is leading to death - not clear
sleep deprivation in humans
1964
17yo agreed to stay awake for 11 days
beat the world record
no caffeine available
he showed marked circadian rhythms in sleepiness
occasional hallucinations
showed ataxia (inability to perform coordinated movements)
increased irritability
speech difficulties
deficits in attention and memory
reduction in body temperature
can you catch up on missed sleep
Randy was allowed to sleep again
on first night he slept for 15 hours
by the end of the week he was getting 9 hours
a week after experiment he was getting 7h
what happened when randy fell asleep after the experiment
his body prioritised REM sleep and deep NREM sleep
there was less light sleep
so this tells us these types of sleep are important
effect of sleeplessness in crashes
multiple crashes due to sleep deprivation
more than 20% of fatal crashes involve a driver who was drowsy
sleep deprivation impairing performance
ppts sleep deprived for 28 hours
another group was given alcohol steadily
hand-eye coordination was assessed repeatedly
RESULTS
decrease in performance as a result of being awake for 24 hours was equivalent to having a blood alcohol concentration above the drink drive limit
the way we sleep is linked to health
the way u sleep is linked to
ADHD
ASD
anxiety
depression
PTSD
conduct disorder
effect on short sleep on immune system
short sleep compromises the immune system
sleep assessed for a week in ppts
ppts were given nasal drops - virus that causes common cold
those who got up to 6h sleep were more likely to get a cold than those who slept for longer periods
BUT
when sleep length was reported by self report, these associations weren’t found - results from studies may depend on whether we use objective or subjective measures
possibility: ppl aren’t good at estimating their own sleep length
cost of not getting enough sleep
cost of insufficient sleep on the economy
decrease in potential in adolescence
decrease in performance
absenteeism
insufficient sleep costs the UK £40 billion each year
theories of sleep
evolutionary theory
restorative theory
information/memory processing
evolutionary theory
during sleep we become less aroused
we become vulnerable to predators
lack movement - cannot escape quickly
sleep as a way to conserve energy
sleep might have evolved to conserve energy
sleep conserves energy during times of inefficiency
body temp decreases during sleep
muscular tension, blood pressure and rate of respiration is reduced
when we are REM sleep deprived there may be excessive heat loss
when we are NREM deprived we need to use excessive energy in oder to maintain temperature
what are some exceptions
REM sleep doesn’t save any energy compared to being awake
dolphins
- one hemisphere goes into deep sleep
- the other stays awake
- they can keep swimming so they are not conserving much energy
update of evolution of sleep
different behavioural states allow for energy to be allocated optimally to vital biological processes
when awake we can use energy for reproduction
when we sleep we use energy for neural network reorganisation and growth
restorative theory
when we are asleep we restore our brain and body
when we sleep our metabolic requirements are replenished
growth hormone is released to the greatest extent during our deep sleep - allows for cell reproduction
sleep allows us to restore hormone and neurotransmitter levels
sleep allows growth of synaptic connections
against restorative thoery
protein synthesis occurs 24h a day, not just during N3 altough it seems to peak in N3
amount of sleep does not appear to decrease when our level of daytime activity decreases
theory predicts that more active species will sleep longer. however, 1 of the least active creatures, the sloth, sleeps for about 20h per day
metabolic homeostasis
metabolic - the chemical reactions in our cells
homeostasis - balance, maintaining equilibrium
the role of sleep in clearing metabolites from brain
sleep in mice
during sleep, there was a 60% increase in interstitial space, resulting in an increase in the exchange of cerebrospinal fluid with interstitial fluid
this allowed the clearance of beta amyloid from the brain
toxins build up in the brain when we are awake - beta amyloid - an amino acid centrally involved in Alzheimer’s
when we sleep certain brain cells (glial cells) shrink and this allows more space for fluid to remove toxins from brain
scientists who imaged the brain of mice, showed that the glymphatic system became 10x more active when them mice were asleep
sleep in supporting immune system
defence against pathogens is mediated by central nervous system and changes to concentrations of immune signalling molecules called cytokines
concentrations of cytokines naturally vary with sleep wake cycles
cytokines can cause immune system to increase t cells to help fight infections
information and memory processing theory
sleep may have evolved for learning and memory consolidation
the ability to learn and memorise info is metabolically expensive
during sleep, the info coming through sensory systems is minimal - metabolic demands associated with this are low
-during this inactive phase, new brain circuits are laid down
how is memory consolidated during the mind
during sleep, newly formed memory representations are reactivated
this reactivation aids in the redistribution of memories from STM in a part of the brain called the hippocampus into LTM in areas of the cortex
this reactivation process occurs during NREM sleep
REM sleep is thought to stabilise reactivated memories to ensure they remain in LTM, integrated with other relevant memories
studies supporting info memory theory
young adults reporting poor sleep quality also performed less well on attention tasks
ppts 16-19 who get less sleep and whose schedules differs most at the weekend compared to the week get a lower grade point average
difference in terms of schedule from weekdays to weekends is called a social jet lag - operating on a different schedule on our days off
sleep important for insight
mendeleyev
he was struggling with some of the rules in order to develop the table and the key rule came to him in a dream
support for sleep resulting in insight
3 groups
each had 3 training blocks and 10 final blocks
the difference was the period in between their training and final block
they were either asleep from 11pm-7am
awake from 11pm-7am
or awake in the day from 11am-7pm
in the training block ppts had to analyse and 8 digit string of 1s, 4s and 9s from left to right
task was to work out the rules: can u see what the rules are
if digits are the same, the response should be the same digit
if digits were different the response should be the remaining digit
RESULTS
20% of those who were awake during the day and awake during night got answer correct
60% got correct response when sleeping
can brain respond to stimuli when asleep
our brain can respond to auditory stimuli when we are asleep
k complexes are present during N2 sleep
ppts asked to remember target names whilst they were awake
then when they were asleep names were played to them, including their own name and other controls
k complexes appeared in N2 when names were played
k complexes responses to target names were larger and more reliable than control names
largest k complexes to their own name
can we learn when we are asleep
new born babies were played tunes
when tunes were played, experimenter gave air puff to baby - air blown gently into their eyes
upon hearing the tune they learnt to scrunch up their eyes
unlikely more complex infor can be learnt this way
attempts to learn new info while asleep - focusing on other age groups have failed
