Lack of sleep can make you selfish, claims study

Researchers conducted three studies in the US looking at this 'selfish' effect, analyzing changes in neural activity and behaviour benefiting others, and found it was prevalent even after a small loss of sleep.

The study also suggested that insufficient sleep not only harms an individual`s mental and physical well-being but also jeopardises interpersonal bonds and even the altruistic sentiment of an entire nation.

In one section of the new study, the researchers found that charitable giving dropped by 10% in the week following when residents in most states lose one hour of their day -- a drop not seen in states that do not change their clocks.

It involved mining a database of 3 million charitable donations made in the United States between 2001 and 2016.

The new research shows that a lack of sleep not only harms an individual`s health, but also degrades social interactions between individuals and, ultimately, the fabric of human society itself, said Matthew Walker, one of the researchers of the study.

"How we function as a social species -- and we are a social species -- appears to be profoundly dependent on how much sleep we get," he said.

The researchers scanned the brains of 24 healthy volunteers using a functional magnetic resonance imager (fMRI) after eight hours of sleep and after a night of no sleep.

They discovered that after a sleepless night, areas of the brain that form the theory of mind network, which is engaged when people empathise with others or try to understand other people`s wants and needs, were less active.