Less sleep makes you feel less positive, happy: study
LifeStyle
Going to bed just one hour later than usual is enough to make you miserable
(Web Desk) Staying up too late could make you feel less enthusiastic about life the next day, even if you only lose an hour of sleep.
Getting less sleep than usual, regardless of the number of hours, makes people feel less positive and happy, a scientific review has found.
Researchers looked at 154 studies, spanning more than 50 years, and including more than 5,000 people aged seven to 79, on sleep deprivation.
Sleep restriction, where people got less sleep than normal, was found to significantly reduce their positive feelings, like enthusiasm and happiness.
People's positive emotions appeared to take the biggest hit if they got four hours less sleep than normal - but they felt less positive from any reduction in sleep at all.
Losing out on sleep was also linked to a higher risk of feeling anxious and depressed, although this effect was smaller.
Dr Jo Bower, who led the study from the University of East Anglia, said: 'These results matter because people who feel less positive enjoy things like seeing friends, going to exciting events or watching their favourite television show less, which puts them at greater risk of depression.
'They are typically less motivated to socialise, so are at greater risk of isolation and loneliness.
'In our largely sleep-deprived society, people often stay up late, and we don't want them to be afraid of doing so, but this analysis suggests less sleep will have an effect on mood.'
The scientific review, published in the journal Psychological Bulletin, found people's positive emotional state is unsurprisingly most affected by sleep deprivation - like being forced to stay awake overnight, or over several nights.
But researchers also looked at the effects of getting less sleep than usual and getting woken up through the night.
Perhaps reassuringly, for parents of young children who routinely wake them up, the latter was not linked to a significant rise in negative emotions - unlike the other two types of sleep loss.
However, this may have been because there were too few studies on this to show a link.
Sleep restriction, meaning less sleep than normal, which could be caused by an unusually late night or early morning, was also linked to people's emotional reactions.
The studies tested this with experiments including showing people upsetting pictures like a snake or someone pointing a gun, or asking them to do stressful tasks like mental arithmetic.
People who got less sleep reacted less strongly, and less negatively, suggesting they cared less.
Surprisingly, a complete lack of sleep and less sleep were both linked to more of a reduction in positive emotions than an increase in negative feelings like sadness or worry.
This could be because sleep deprivation causes the body to release higher amounts of the stress hormone cortisol, which activates a fight-or-flight response in the nervous system.
This response leads to physical symptoms of anxiety, including rapid breathing and high heart rate.
Additionally, not getting enough sleep alters the amount of serotonin the brain produces, which regulates mood.
