We all know that a lack of sleep can put us in a bad mood, but a new study has found it can actually make people more selfish too.
US researchers also found a link between daylight savings and charitable donations.
University of California Berkeley’s Eti Ben Simon, who authored the study, tells Nine to Noon a lack of selflessness is determined to a degree by sleeplessness.
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He argues that adequate sleep should now be seen as a human right that we must fight to ensure both personal and societal health.
“We had an experiment with where people didn't sleep for one night, we had an experiment where people just track their natural sleep from night to night. And then we also focused on daylight savings time, which makes us lose about an hour of sleep for a single night. In all of these studies we found the same effect - that lack of sleep blocked this innate desire humans have to help each other.”
The researchers were surprised to find that even one hour of lack of sleep in one night had this effect.
"We analysed a large donation database that was made in the US, in the past 15 years, more than 3 million donations.
“We found that the week right after the switch to daylight saving time, people donate about 10 percent less money than any other week of the year. So, every little dent in our sleep has a measurable effect on how generous we are to each other.”
Functional MRIs used in the study identified a difference in how the brain processed social information with, and without, sleep.
“When we had participants after one night of no sleep in the scanner, we saw that regions of the brain that were typically active when we think about what other people might want or need are far less active without sleep” he said.
“So basically, our ability to even consider what other people might want is impaired. And we think that that's part of the reason why we're effectively less likely to help them.”
This effect is a social impact, with the amount of sleep deprived people determining the health of society at large.
“It really does help shape the kind of societies we live in,” Simon says.
In the US, and many other industrialised countries, more than half of people report not getting sufficient sleep during the work week.
But he says chronic sleep loss began around the 1970s and is now accepted as the norm. But, he argues, people should fight back, as the need for adequate sleep is a fundamental human right.
“It used to be pretty rare to see people sleep less than six hours, around 11 to 12 percent in the 1940s. And now that number is more than 30 percent. So, more than tripling the amount of people not getting the sleep that they need. And I think there is a lot we can do to normalise efficiency back. This is not sort of a luxury event to get sufficient sleep. This should be a basic human right. And I think we're seeing more and more of the implications of that.”
The optimum number of hours sleep per night we should be having is 9, something he personally tries to achieve.
“I know first hand, even before starting to do sleep deprivation studies, how critical it is for me to get the sleep that I need to be productive and helpful and to have positive mood.
“This is exactly what we see across studies as well, that all the major physiological and psychological systems of the body needs sufficient sleep.”