Sleep - sleep deprivation

Reasons for sleep deprivation
Some examples - Shift work (effects your sleep work cycle and can lead to sleep deprivation), sleep disorders, lifestyle (internet, mobile phones), family commitments (young children), anxiety, stimulants, stress, health conditions
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How much sleep do we need?
The way to test this is to carry out sleep deprivation studies. The studies are important as they reveal the functions of sleep, they also are useful in informing us about the impact of sleep loss
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What is sleep deprivation?
Sleep deprivation is an active process where we actively restrict our sleep either by going to bed late, waking up early or getting up through the night.
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Total Sleep Deprivation
short term, being awake for up to 45 hours. Long term, more than 45 hours
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Partial Sleep Deprivation
sleep is restricted- can be for short term (acute), long term (chronic)
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Sleep Fragmentation
going to sleep at the usual time but your sleep is disrupted throughout the night.This means that you might end up spending more time in the lighter stages of sleep e.g. stage 1. People who experience sleep fragmentation don't feel rested
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Signs that you are sleep deprived
Difficulty making simple decisions, difficulty concentrating, falling asleep, weak immune system, feeling more emotional than usual, still feeling hungry after eating
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Consequences of sleep deprivation
Cognitive function, weight management, reproductive system, immune system and emotional wellbeing
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Van Dongen et al (2003) - the sleep deprivation periods used
TSD, 4 hours, 6 hours and 8 hours of sleep
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Van Dongen et al (2003) - What were the tasks
Psychomotor Vigilance Test, Digit Symbol Substitution Task, Serial Addition Subtraction Task, Stanford Sleepiness Scale
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Van Dongen et al (2003) - how did participants perform in the Psychomotor Vigilance Test
those in the TSD condition took longer, reaction time was slower. The more sleep they had the better their performance was on this task.
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Van Dongen et al (2003) - how did participants perform in the Digit Symbol Substitution Task
TSD did significantly worse. Whilst the more sleep they had the better they performed.
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Van Dongen et al (2003) - how did participants perform in the Serial Addition Subtraction Task
TSD did significantly worse.
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Van Dongen et al (2003) - how did participants rate in the Stanford Sleepiness Scale?
TSD are clearly able to identify that they are sleepy. However, what’s really interesting is that the other groups with restricted sleep are not really identifying themselves as sleepy even though clearly show that they are performing poorly.
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Van Dongen et al (2003) - same study - sleep deprivation and sleep architecture - stage 1
very little differences in the amount of time spent in this stage of sleep between the conditions.
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Van Dongen et al (2003) - same study - sleep deprivation and sleep architecture - stage 2
You can see that those who has restricted sleep to 4 hours spend less time in stage 2 sleep.
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Van Dongen et al (2003) - same study - sleep deprivation and sleep architecture - stage 3 & 4
little different in amount of time spent in SWS. Pp's are sleeping different hours but all spending similar amount of time in SWS. This shows how important SWS is, must serve some kind of important function
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Van Dongen et al (2003) - same study - sleep deprivation and sleep architecture - REM
some differences.Those restricted to sleep 4/6 hours spend less time in REM sleep than 8 hours. shows that we still want to maintain REM sleep we can spend less time in it if our sleep is restricted.probably because want to spend more time in SWS
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Sleep deprivation and sleep homeostasis
When you are deprived of sleep,sleep homeostasis continues to build&keeps increasing.important because this sleep homeostasis is closely related to SWS, the reason for this is that the greater the sleep pressure the more time you will spend in SWS
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Yoo et al (2007) - participants and participants sleep deprivation
26 health individuals aged between 18-30 years were assigned to either a sleep deprivation group or a control group. In the sleep deprived group participants were awake for 35 hours, in the control group participants were not deprived of sleep.
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Yoo et al (2007) - what participants did
All participants performed an emotional stimulus viewing tasks whilst their brains were scanned using fMRI.
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Yoo et al (2007) - what they found
the control group and the sleep deprived group showed increased activation to negative stimuli. But the sleep deprived group 60% greater amygdala activity in comparison to the control.
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Yoo et al (2007) - conclusions
SD and mood is that we become more sensitive to negative events when we are sleep deprived. This is because of the amygdala, we all the know that this region of the brain is involved in emotional responses.
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Sleep deprivation and weight management - background
Getting sufficient sleep can help keep your appetite in check,curb cravings&reduce late night snacking.Research has shown that partial sleep deprivation can have a significant impact on weight management-how easily it is gained, lost&maintained.
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Sleep deprivation and weight management - hormones (Taheri et al., 2004)
2 key hormones involved in regulating hunger and appetite(ghrelin&leptin).Sleep is important for regulating our metabolism&regulating these hormones.Sleep deprivation disrupts the levels of these hormones-are critical in regulating hunger&appettite
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Ghrelin (Taheri et al., 2004)
Ghrelin is a fast-acting hormone, produced in cells of the stomach, which spurs appetite and drives us to eat. Ghrelin may particularly increase appetite for high-calorie foods. When the body is deprived of sleep, production of ghrelin increases.
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Leptin (Taheri et al., 2004)
Hormone-suppresses appetite by communicating to receptors in brain that body has the energy it needs to function, doesn't need more.When leptin levels lower than normal, less likely to feel full after eating.Low sleep suppresses leptin production
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Increase in appetite is linked to...
obesity
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Orzeł-Gryglewska, 2010
Sleeplessness is related to the changes in the immune response&the pattern of hormonal secretion, of the growth hormone, especially.
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Sleep deprivation and immune system
Our immune system defends our body against infections and viruses. Natural killer cells help the body to fight viruses, infections, illnesses.
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***Heiser et al., 2000***
Sleep deprivation and recovery sleep lead to a reduction in natural killer cells
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Dawson & Reid (1997) - participants
Pp's participated in 2 experiments. Pp's were kept awake for 28 hours (from 8:00 until 12:00 the following day). Pp's were asked to consume 10–15 g alcohol at 30-min intervals from 8:00 until their mean blood alcohol concentration reached 0.10%.
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Dawson & Reid (1997) - how measured
The researchers measured cognitive psychomotor performance at half-hourly intervals using a computer-administered test of hand–eye coordination (an unpredictable tracking task).
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Dawson & Reid (1997) - what found
The longer you are awake the worse the performance, this is very similar to the performance you see when individuals consume alcohol and yet there is a great emphasis on not driving after drinking in comparison to driving when tired.
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Methodological limitations of sleep studies
Napping Practice effects Divergence between subjective and objective measures. Differences in paradigms make it difficult to make comparison, especially for partial sleep deprivation. Individual differences
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Can we overcome sleep deprivation?
You can take a nap or have a coffee to counteract fro the effects of sleep deprivation.
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Ferrara & De Gennaro, 2001
There is no real consensus for how much sleep we need. Some suggest between 7-8 hours. Other suggest more or less.
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Individual differences - influence how we respond to sleep deprivation
Age Gender Circadian Rhythm Genetics Sleep homeostasis Health conditions Longer sleepers/shorter sleepers
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Summary
Many different paradigms are used in sleep deprivation studies. A variety of measures are used to assess the impact of sleep deprivation. Evidence indicates that sleep deprivation affects a whole range of bodily functions. Methodological limitations
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Tips for sleep hygiene
Have a consistent sleep and wake time Get regular exercise each day Get regular exposure to sunlight Keep the temperature in the bedroom cool Keep the bedroom quiet when sleeping Keep the bedroom dark enough to facilitate sleep Keep feet & hands warm
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Sleep hygiene - things to avoid
Play computer games and watch television in your bedroom Avoid using your phone Have caffeine in the afternoon/evening Use alcohol to help you sleep Take sleeping pills. Napping longer than 30mins
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***Lim & Dinges, 2008***
propose that sleep deprivation leads to an increase of errors of omission and commission, slowing of response times and an increase of the time-on-task effect (where performance declines during a test because of fatigue or boredom).
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***Boonstra et al., 2007***
Sleep deprivation is linked to increased levels of adenosine that has a general inhibitory effect on neural activity
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***Buxton et al., 2012***
There is evidence that sleep must be of adequate length and physiological continuity to avoid predisposing people to adverse health problems, such as obesity and diabetes.
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***Brunner et al., 1990***
REM sleep rebound has been found in the 2 recovery nights following only 2 nights of partial sleep deprivation of 4 hours
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***Independent research - Pilcher & Huffcutt, 1996***
Meta-analysis-aimed to quantitatively describe the effects of sleep loss.Results suggested overall sleep deprivation greatly impairs human functioning.also found sleep deprivation has a stronger effect on mood than either cognitive or motor performan
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***Independent research - Penetar et al., 1993 - background***
Study investigated whether caffeine reversed alertness and mood changes that were produced by prolonged sleep deprivation.
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***Independent research - Penetar et al., 1993 - found***
It was found that caffeine reversed sleep deprivation changes in three subscales of the POMS which were vigor, fatigue and confusion. Also, values were produced that were similar to fully rested conditions on Visual Analog Scales.
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How much sleep do we need?

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The way to test this is to carry out sleep deprivation studies. The studies are important as they reveal the functions of sleep, they also are useful in informing us about the impact of sleep loss

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What is sleep deprivation?

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Total Sleep Deprivation

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Partial Sleep Deprivation

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