Is WhatsApp keeping us up way past our bedtime? Answer is yes, say doctors at Bengaluru-based National Institute of Mental Health and Neuro Sciences (Nimhans). A study has revealed that the use of the internet for Facebook and WhatsApp is making people put off sleep by more than one and a half hours (100 minutes) every day and leading to sleep apnoea to psychological and neurological disturbances. In a 2016 study by the Service for Healthy Use of Technology (SHUT) clinic at Nimhans, researchers found that internet use was also making people wake up 90 minutes later. The study, published in January in the Indian Journal of Occupational and Environmental Medicine, also found that while the quality of sleep was above average, most people usually checked their phones and tablets at least four times after going to bed. The prescription: shut off devices as you near bedtime. Sleep disorders and sleep loss, say doctors, can contribute to conditions varying from heart disease to anxiety. A 2015 study by a private hospital in Gurgaon revealed that 90% of young heart attack victims were those who did not sleep well. The application keeping most people up was WhatsApp (58.5%), says psychiatrist Dr Manoj Kumar Sharma, additional professor at SHUT clinic and one of the lead researchers of the study. "This was followed by Facebook usage (32.6%). Messenger applications other than WhatsApp and Hike were used rarely (65.7%).Gmail was shown to be frequently used by participants (45.3%)," he adds. The research, says Sharma, also showed that 60% of the participants used their mobile phone along with devices such as desktops, laptops and tablets at home as well; 42% of the participants acknowledged that they put off work just to be on the internet. Dr Suresh Kumar, neurophysician at Chennai-based Sree Balaji Medical College and Hospital, says he is seeing more patients with "delayed sleep phase syndrome (DSPS)", where instead of the usual sleep cycle of eight hours from around 10 pm to 6 am, people are going to bed only by 3 am and waking up at 11 am. "It's not just adults; children too are sleeping at 1 am," he says. Doctors say people with DSPS, otherwise referred to as "social jet lag", are not successful at maintaining normal 9-5 workdays and complain of fatigue, headache, decreased appetite or depressed moods. Suresh suggests that those who find it difficult to sleep can schedule a fixed wake-up time even on weekends. "We also ask them to try and advance their bedtime by 30 minutes every three days until they hit a regular sleep cycle." Sharma advises his patients to shut off all gadgets an hour before sleeping and switch to something more old fashioned like reading, or even having a conversation with other people in the house. Nimhans, he adds, is now working on an app which will analyse time spent on the internet and caution users about cutting down.