It is already known that not getting enough sleep can have a detrimental effect on a person's weight. However, new research has found that the consistency of a person's bedtime and waking up time may also play a role.

US researchers followed the progress of 300 young women over a number of weeks.

They found that those who got less than 6.5 hours of sleep per night, or more than 8.5 hours, tended to have higher body fat. However, they also found that those who went to bed and woke up at roughly the same time every day tended to have lower body fat.

Those with more than 90 minutes of variation in their bedtime and waking up time during the week had higher body fat than those with less than 60 minutes of variation.

In fact, the time a person woke up seemed to have a particularly strong link to body fat, with those who woke up at the same time every morning having lower body fat in general.

"We have these internal clocks and throwing them off and not allowing them to get into a pattern does have an impact on our physiology," the researchers from Brigham Young University noted.

Meanwhile, they also found that sleep quality had a role to play. Those who enjoyed a good quality of sleep tended to have lower body fat.

"Sleep is often a casualty of trying to do more and be better and it is often sacrificed," they added.

Details of these findings are published in the American Journal of Health Promotion.