They found that those who slept for less than six hours a night or more than nine put on more weight than those who slept for seven or eight hours each night. The research found those who did not get enough sleep gained almost 2 kg compared to those who slept for the recommended number of hours. Also, those who had too much sleep gained 1.58 kg more than those who slept for the recommended number of hours over six years. The research found that things were worse for people who got less sleep as they were 35 per cent more likely to gain 5 kg over six years than those who had seven or eight hours sleep.
The reason for this was that sleep affects hormones levels, especially those involved in appetite and feeling full after a meal, it said.
Jean-Philippe Chaput of Laval University, Canada, who carried out the study said,'' Our study provides evidence that both short and long sleeping times predict an increased risk of future body weight and fat gain in adults.'' ''Since preventing obesity is important, a pragmatic approach adding sleep hygiene advice to encouragement towards a healthy diet and physical activity may help manage the obesity epidemic,'' he added.