A team of international researchers has found that people who sleep for less than six hours a night - or more than nine -- put on more weight than those who sleep for seven or eight hours daily, The Daily Telegraph reported on Wednesday.

The reason that the amount of sleep a person gets can govern his or her weight is because sleep affects hormones levels, especially those involved in appetite and feeling full after a meal, the study has suggested.

According to lead researcher Jean-Philippe Chaput of Laval University in Quebec, "Our study provides evidence that both short and long sleeping times predict an increased risk of future body weight and fat gain in adults.

"Furthermore, these results emphasise the need to add sleep duration to the list of environmental factors that are prevalent in our society and that contribute to weight gain and obesity.

"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."

The researchers came to the conclusion after analyzing the sleep patterns of 276 adults aged between 21 and 64 over a period of six years.

In their study, the team found that the participants who did not get enough sleep gained almost two kgs compared to those who slept for the recommended number of hours. Similarly those who had too much sleep gained 1.58 kgs more than those who slept for eight hours.

Short sleepers were found to be 27 per cent more likely to become obese and long sleepers were 21 per cent more likely than those had an average night's sleep.

Moreover, the study found that things were worse for people who got less sleep as they were 35 per cent more likely to gain five kgs over six years than those who had seven or eight hours sleep.