3. Sleep Deprivation

Question 1

reasons for sleep deprivation

Answer 1

• shift work
• lifestyle (24/7 society)
• family commitment (young children)
• anxiety (increased arousal)
• stimulants
• sleep

Question 2

what are the signs of sleep deprivation

Answer 2

• difficulty making simple decisions (easy options)
• difficulty concentrating
• falling asleep (napping)
• feel hungry
• more emotional
• negatively effects reproductive system (quality of sperm)

Question 3

what is sleep deprivation?

Answer 3

• total sleep deprivation (TSD)
• partial sleep deprivation (PSD)
• sleep fragmentation
• not insomnia (struggle to get to and maintain sleep)
• sleep deprivation is where we actively restrict our sleep by going to bed late and/or waking up early

Question 4

total sleep deprivation (TSD)

Answer 4

• long term = > 45h
• short term = < 45h
• difficult to run studies without the use of stimulants as people take microsleeps (dont even know they are doing it) - ethical issues

Question 5

partial sleep deprivation (PSD)/restricted sleep

Answer 5

• acute = short term
• chronic = long term
• more common model (partial sleep deprivation/restricted sleep)

Question 6

sleep fragmentation

Answer 6

• going to sleep at the usual time but sleep is disrupted throughout the night
• may end up spending more time in the lighter stages of sleep/less time in deep sleep

Question 7

sleep deprivation: cognitive function

Answer 7

Van Dongen et al (2003)

• used a range of deprivation periods (TSD, 4, 6, 8h sleep)
• assessed a range of cognitive tasks (attention, sleepiness, addiction, subtraction)
• attention (psychomotor vigilance test) = TSD resulted in longer reaction times. the more sleep they had the better their performance
• addition/subtraction (serial addition/subtraction task & digit symbol substitution task) = same pattern as above
• sleepiness (objective measure) = TSD say they feel tired, but those who were PSD do not say they are tired yet still perform worse than the 8h condition
• sleepiness scale doesn’t correlate to cognitive measures - individuals are not very good at knowing when they are tired
• cant say its down to the task that people are performing differently as there are multiple

Question 8

sleep deprivation: architecture

Answer 8

Van Dongen et al (2003) - 4, 6 or 8h sleep
- stage 1 = very little different found
- stage 2 = restricted sleep (4h) spend less time here
- stage 3 and 4 = very little difference here (shows how important this stage is as when sleep deprived individuals don’t sacrifice sleep here)
REM = those restricted to 4 and 6h sleep have signficiant reductions in REM sleep

4h = lowest Delta activity, reducing to 60% or the normal rates at one stage

Question 9

sleep deprivation: emotional wellbeing

Answer 9

Yoo et al (2007) - 18-30 year olds (N = 26) assigned to sleep deprivation (awake for 35h) or control conditions

• emotional stimulus task was performed whilst an fMRI was recording the small changes in blood flow of the brain
• 100 images ranging from positive to negative (spectrum)
• the sleep deprived group showed 60% more amygdala activation to negative stimuli (more sensitive to negative events)
• amygdala is influences by the medial prefrontal cortex (MPFC) - inhibitory top down control of amygdala (acts as a break) - seems to be disconnect here

Question 10

sleep deprivation: weight management

Answer 10

Van Cauter et al., (2005)

• good sleep helps keep appetite in check, stop cravings and reduce late night eating. it can determine how easy or hard it is to lose weight
• two types of hormones that are involved in regular hunger and appetite, important for regulating metabolism also:
  1. Ghrelin (increases hunger)
  2. Leptin (suppresses hunger)
• can change our appetite but also our choice of food
• when you are sleep deprived Ghrelin increases appetite for calorie rich food, leading to poor choices
• when you are sleep deprived, the production of leptin is suppressed (even short term deprivation)
• linked to obesity and public health
• even if you eat healthy but are are also sleep deprived, the body retains energy (fat) as it is low on energy (sleep)

Question 11

sleep deprivation: immune system

Answer 11

• same impact as stress, weakens the ability to defend against infection and viruses
• sleep deprivation reduces the amount of natural killer cells that help fight against illness, infections and viruses

Question 12

sleep deprivation: neurodegeneration

Answer 12

lack of sleep leads to a build up of a toxis chemical called beta amyloid (which is associated with the development of Alzheimer’s)

• SWS associated with removal of these chemicals
• less SWS = more beta amyloid = higher risk of dementia

Question 13

sleep deprivation vs alcohol consumption

Answer 13

Dawson and Reid (1997)

• participants where either kept awake for 24h or recieved 10-15g of alcohol at 30 min intervals until their mean blood alcohol level was .1%
• cognitive psychomotor ability assessed using hand eye coordination test delivered on a computer
• the longer you are awake, the worse the performance
• similar to the performance you see when drinking alcohol
• think drink driving

Question 14

methodological limitations

Answer 14

• don’t take napping into account, how would you control?
• practice effects = tasks associated with cognitive function can be performed better by some individuals compared to others
• divergence between subjective and objective measures = people aren’t good at knowing how tired they are so subjective measure may be impacted
• differences in paradigms used makes it hard for comparison = partially sleep deprived > time, amount, location of sleep
• individual differences = everybody’s sleep needs are different, you can have morning/evening types, could have consumed caffeine or get affected by it differently, age)