Sleep is the state of natural rest, which refreshes the body and the brain. It is already known that those who skip sleep regularly have both physical and mental health problems.
A new study by researchers from the University of California has found brain activity associated with mental illness in healthy people who missed a single night's sleep.
The researchers asked volunteers to miss a night's sleep and stay up until 5 p.m. the following day. Next, the scientists scanned their brains as the participants viewed gory images such as mutilated bodies or children with tumours.
The sleep-deprived group showed increased activity in the amygdala, an area of the brain involved in processing fear and other emotions, reported the online edition of the New Scientist.
The heightened activity is no surprise since there is a known link between tiredness and emotions.
But the amygdala appeared to be more active because connections with the prefrontal cortex - an area of the brain that normally damps the amygdala down - were disrupted.
Similar disruption is seen in patients with depression and post-traumatic stress disorder, the researchers said.