The Effects Of Sleep Deprivation
The Effects Of Sleep Deprivation
Chris Idzikowski (Director of the Edinburgh Sleep Centre) gives expert video advice on: What is sleep deprivation?; What is sleep restriction?; Does sleep deprivation have cumulative effect? and more...
What is sleep deprivation?
Sleep deprivation is a phrase that is just that: it's preventing someone from sleeping. So I might do it experimentally with people to see what the effects of sleep deprivation are honestly on daytime function.
Does sleep deprivation have cumulative effect?
Yes the effects of sleep restriction do build up over the nights and days. One thing to be aware of though, is that doesn't mean that you are necessarily always on the decline after not getting one night's sleep. How alert we are in our mental performance and physical performance is partly driven by the biological clock, so when that doesn't have that twenty-four hour cyclicity. Maximum sleepiness is at four in the morning but gradually rising throughout the day apart from that siesta block in the afternoon. If one is sleep deprived totally, no sleep that night or sleep restricted, the following day that rhythm will still be operating so one's alertness will still improve throughout the day, but it will be a step lower than it usually is. If one then gets another night's sleep deprivation or more sleep restriction, again the same will follow the next day. That rhythm will remain, but it will be a step lower. Sleep tends to become much more intense upon recovery. So when you are allowing yourself more sleep, the stage that tends to disappear is light sleep and a huge amount of the deep sleep is recovered; a lot of the rapid-eye-movement sleep is recovered. So we are designed to accommodate periods of disturbed sleep, say when looking after children as families and so on and that's where weekends are good. As long as there's an opportunity for recovery sleep relatively soon after the disturbed sleep, then we assume that's the way we are designed to work.
What is the minimum amount of sleep we can survive on?
The shortest sleepers tend to be around three hours, three to four and a half hours, so there's an element of that. But in fact there is some evidence the long sleepers-I have to say a disadvantaged group in society-I say the nine hour sleepers, you can only manage on nine and nobody believes that they can't manage on eight. But, in fact, in sleep deprivation, in emergency situations, those long sleepers tend to tolerate the reduced sleep better than the short sleepers. But if I was looking for minimums, I would always think in terms of deep sleep, when you usually get around three hours deep sleep during the night, say well two and a half to three hours deep sleep during the night. One needs to get that in. It would be good to get the rapid eye movement sleep in and that is likely to happen if one is only allowing short amounts, somewhere around there.
How does lack of sleep affect us?
I'd always say the impact on the body is pretty mild and most of the recovery effects can be gained by just resting. But as far as the brain is concerned, concentration and vigilence are usually affected by even short amounts of sleep restriction. With sleep depravation over and above that, one gets other higher order effects coming in, serious risk taking and suggestibility increase but also things like saying the same thing or working a solution the same way even though the conditions have changed and just stereotypical responses continue in the same way all occur with sleep restriction.
Can you die from lack of sleep?
The most likely way of dying from not sleeping enough is by falling asleep at the wheel, that's where most accidents - most deaths - would occur. Although we know from the animal experiments that it's possible to kill animals through sleep deprivation. If, as a pharmacologist, I'd stand back on that and think about well, how much sleep deprivation should a human have, it's a lot. Meaning at least a year's worth of no sleep whatsoever and that just generally doesn't happen.
How does lack of sleep affect reaction time?
Sleep deprivation will impact on reaction times partly by causing sleepiness, with the sleep just sort of bursting in as micro sleeps and creating a problem with the response but in general also increasing reaction time.
How does sleep deprivation affect work performance?
Sleep deprivation and sleep restriction just don't help work at all. Mainly because you can't concentrate as well, it's more difficult to recall things, one might take more risks, one might become more suggestible to what others might be saying, it's harder to generate new solutions. Everything just starts to go wrong. For an insomniac, it even gets worse, because if they start worrying about not getting enough sleep, then they also think about sleep impacting on slurring and concentration as well.
What are the long term health implications of sleep deprivation and restriction?
With sleep deprivation, it is so difficult for people to be sleep deprived for long term. I never see a real consequence to that. Sleep restriction is the issue in terms of physical effects not necessary. Mental effects, yes, higher association with depression and other psychiatric disorders. We do not know which way around it is, the chicken or egg. Whether both disorders are actually disturbing the sleep or the disturbed sleep is causing the disorders or a mixture of the two. In terms of appetite control and because of the impact on health there, yes, there are going to be long-term effects.
Why do we become irritable when we have a lack of sleep?
There is a certain degree of higher order functions that are affected by sleep deprivation. Irritability and hostility tends to be something that we prevent happening in society, so if higher order functions are a bit impaired that sort of behavior is released more readily.