Sydney, May 6 : Lack of sleep can affect mental health, causing anhedonia (or loss of pleasure), anxiety, anger and significantly increasing the risk of depression, says a global study of more than 350,000 teenagers. Sleep patterns around the world have been disrupted as screen time increases and sleep routines change with COVID-19 self-isolation requirements. The results, published in the journal Sleep Medicine, connect less sleep with a 55 per cent increased chance of mood deficits and double the risk of reduced positive mood. From Asia to Australia, New Zealand, Europe and North America, sleep clearly was a modifiable risk factor that can improve or depress mood in adolescents, according to the researchers. "Sleep duration significantly predicts mood deficits on all mood states, including increased depression, anxiety, anger, negative affect and reduced positive affect," said study researcher Dr Michelle Short from the Flinders University in Australia. The researchers found that less sleep linked to an 83 per cent higher chance or anger, 62 per cent increased risk of depressed mood, and 41 per cent higher risk of anxiety. "Fortunately, there are many interventions individuals, family, the community and even public policy can encourage to maintain regular sleep in this at-risk population to reduce the likelihood of these problems spilling over into mental health issues needing clinical treatment," she said. The researchers also recommend increased parental/guardian regulation of sleep and technology use, delayed school starting times, and monitoring academic and other pressures such as out-of-hours tutoring do not impede sleep routine. Dr Short said that "while positive mood doesn't get much attention, it is still clinically relevant as one of the key symptoms of depression in anhedonia (loss of pleasure)." "It is imperative that greater focus is given to sleep as for prevention and early intervention for mood deficits," the study concluded. /IANS