PSYC30020 Lecture Notes - Lecture 13: Cognitive Behavioral Therapy, Sleep Diary, Melatonin
10 May 2018
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Lecture 15
- Inadequate sleep:
- Sleep Deprivation - complete absence of sleep
- Sleep Restriction - shortened sleep time
- Sleep Fragmentation - normal sleep times but poor quality sleep (e.g. with frequent
arousal from sleep). Common in sleep disorders
- Sleep loss = inadequate sleep due to any of the above
- Types of experiments: total sleep deprivation is more likely to demonstrate adverse
consequences but not that common in society; sleep restriction and sleep
fragmentations are much more common in society but experiments much longer and
more costly; epidemiological studies assessing sleep duration and a health outcome
- Sleepiness vs Fatigue:
- Sleepiness - reduced alertness due to increased pressure to sleep: the result of
circadian and sleep homeostasis factors
- Fatigue - decreased capacity to continue a task as a consequence of prolonged work
(time on task)
- Sleepiness contributes to fatigue
- “Tired” is commonly used in society to indicate either, so is best avoided
- Ask sleepy people to lift weights → will fatigue faster
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- Australian Sleep Norms: Sleep Health Foundation Survey 2015, 1050 respondents
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- Do humans sleep less than we used to?
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- Obligatory sleep = amount of sleep we need for optimum functioning
- Optional sleep = extra amount of sleep not really needed for optimum functioning
- Kripke et al., 2001: Cancer Prevention Study II, 1982
- Q asked was, “On the average, how many hours do you sleep each night”. A coded
2-9 in whole digits
- Also asked questions about diet, smoking, obesity, working hours etc
- Mortality data was collected in 1988
- 1.1 million participants
- A total of 32 covariates were entered into the hazards analysis
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- Findings: 8 hours most commonly reported but mortality was lowest with 7 hours,
increased mortality rates with lesser and more sleep relative than 7 hours [robust
finding], more sleep higher mortality rate due to residual confounding [maybe people
sleeping 10 hours in bed have arthritis, got a lot of TNF alphas that’s causing them to
be sleepy and other problems in body, undiagnosed conditions that contribute to
extra time in bed]
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- Neurocognitive effects of sleep loss: Sleep loss impairs performance
- Slower reaction time (Reaction time is only reduced by 35msec after 36 hours of
sleep deprivation)
- While changes in reaction time are relatively small, they can be critical, as for
example when driving at high speeds
- Slower reaction time - small but can be important change
- Reduced vigilance - performance on attention based tasks declines, primarily due to
increased lapses
- Sleep restriction and vigilance:
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- Psychomotor vigilance task (PVT):
- Target changes to red → hit button with finger as quickly as possible → randomly
comes on few seconds or 10 seconds within 10 min period
- 10 min sustained attention/reaction time task
- <270 msec normal, lapse: response >500 msec [daydreaming or asleep]
- Van Dongen et al. Sleep, 2003
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- Performance on PVT as a function of 8 (diamonds), 6 (open squares), 4 (circles), or
0 (filled squares) hours of sleep each night
- Participants randomised to how many hours of sleep and stayed in lab for 2.5 weeks
- 72 hours of continuous no sleep max for the filled squares group
- Slower reaction time – While changes in reaction time are relatively small, they can
be critical, as for example when driving at high speeds
- Reduced vigilance – Performance on attention based tasks declines, primarily due to
increased lapses
- Deficits in information processing – Processing and integration takes longer, short
term memory accuracy reduced
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Sleep deprivation - complete absence of sleep. Sleep fragmentation - normal sleep times but poor quality sleep (e. g. with frequent arousal from sleep). Sleep loss = inadequate sleep due to any of the above. Sleepiness - reduced alertness due to increased pressure to sleep: the result of circadian and sleep homeostasis factors. Fatigue - decreased capacity to continue a task as a consequence of prolonged work (time on task) Tired is commonly used in society to indicate either, so is best avoided. Ask sleepy people to lift weights will fatigue faster. Australian sleep norms: sleep health foundation survey 2015, 1050 respondents. Obligatory sleep = amount of sleep we need for optimum functioning. Optional sleep = extra amount of sleep not really needed for optimum functioning. Kripke et al. , 2001: cancer prevention study ii, 1982. Q asked was, on the average, how many hours do you sleep each night . Also asked questions about diet, smoking, obesity, working hours etc.
