Sleep Flashcards
What is a circadian rhythm?
Our internal 24 hour cycles
What are ultradian rhythms?
Rhythms shorter than a 24 hour cycle
What are the features of circadian rhythms?
> Adaptation
Built into the CNS
Internally regulated
Can be regulated by external cues
What did Kleitman (1939) demonstrate?
That without any external cues people operate naturally on a circadian (24.5 hour) cycle
What biological factors influence circadian rhythms?
> Neural activity
Hormone production
Cell regeneration
How does hormone production influence circadian rhythms?
Most hormone are secreted at different rates at different times
How does cortisol secretion influence circadian rhythms?
Cortisol levels increase sharply in the early morning and gradually reduce throughout the day
What controls the sleep/wake cycles?
The suprachiasmatic nucleus
Where is the suprachiasmatic nucleus located?
In the hypothalamus
How does the suprachiasmatic nucleus (SCN) influence the sleep/wake cycle?
> Visual system registers sunlight decreases
SCN increases production of melatonin
Melatonin reduces activity and makes you feel sleepy
What effect does GABA have on the suprachiasmatic nucleus?
> Excites dorsal
> Inhibits ventral
What are the parameters of brainwaves?
> Frequency (Hz)
> Amplitudes (um)
What are the types of brain wave?
> Alpha
Beta
Theta
Delta
What are the features of waking brain waves?
> Low amplitude
> High frequency
What are the features of brain waves during Stage 1 sleep?
Mostly theta waves
What are the features of brain waves during Stage 2 sleep?
> Sleep spindles
> Brief periods of high amp, high freq
What are the features of brain waves during Stage 3 sleep?
Delta waves
What are the features of brain waves during Stage 4 sleep?
Mostly delta waves
What are the features of brain waves during REM sleep?
> Rapid eye movement
> Otherwise identical to Stage 1
What are the features of REM sleep?
> Decreased awareness threshold
Autonomic arousal
Vestibular activation
Genital arousal
What is vestibular activation?
> Spatial orientation
Balance
Movement
What are the psychological factors associated with sleep?
> Facilitation through sleep
> Impairment through deprivation
What cognitive processes occur during sleep?
> Learning
> Problem solving
What are the cognitive processes thought to be impaired by sleep disruption?
> Attention and memory
> Decision making
Does sleep enhance learning?
Yes
What evidence is there that sleep enhances learning?
> Motor learning
Memory recall
Perceptual motor tasks
What have associative learning tasks demonstrated about sleep?
Learning shows offline consolidation of knowledge acquired (Walker and Stickgold, 2004)
What did Walker and Stickgold (2004) demonstrate?
That after sleep previously acquired knowledge is consolidated
Who demonstrated that sleep consolidates knowledge?
Walker and Stickgold (2004)
Theoretically, why does sleep have consolidation benefits?
Sleep includes the neural reorganisation of memory, improving efficiency of storage and easing recall
What neurological evidence is there that sleep deprivation has an effect on the formation memory?
Sleep deprivation is linked to impaired hippocampal function
What did Wagner et al (2004) demonstrate?
That sleep is either reprocessing or reorganising
What did Dickinson and Drummond (2008) demonstrate?
Bayesian updating is resilient to sleep deprivation
What did Dickinson and Drummond (2008) find?
> Bayesian reasoning task
Sleep deprived / rested
No differences in performance
Differences in strategy
What impact does shift work have?
> Physical measures (stress)
Neurobiological
Cognitive measure of behaviour (arousal and attention)
What did Rouch et al ( 2005) find?
Long term shift work was detrimental to memory, attention and decision making
What did Washburn (1992) find?
> Nurses
Fatigue increases during nightshift
Performance and alertness increase during nightshift
Who demonstrated that performance and alertness in nurses was increased at the end of the night shift?
Washburn (1992)
What did Peacock et al (1989) find?
> Policemen
Fatigue increases during nightshift
Performance and alertness increase during nightshift
Who demonstrated that performance and alertness in policemen was increased at the end of the night shift?
Peacock et al (1989)
What did Muecke (2005) propose?
That at the end of a shift ppl may start using compensatory strategies to boost performance
What did Rickard et al (2008) demonstrate?
Evidence of offline learning may be artefacts of:
> Averaging methods
>Time-of-day testing
What are the methodological limitations of shift pattern studies?
> Before-after designs
Shift length
Cross comparisons
What are the limitations of before-after designs wrt shift pattern studies?
Usually conducted once, when one group is going off shift and one group is going on. Doesn’t look at same group performance
What are the shift length limitations of shift pattern studies?
Most studies don’t control for shift length, combinations, speed of rotation or direction of rotation
What are the cross comparison limitations of shift pattern studies?
> Failure to detail differences in task requirement on-job
> Don’t control for levels of physical activity on shift
