Sleeping takes up a good portion of our lives, yet most of us don't give much thought to just how important good-quality sleep is to our health and wellbeing. Missing out on a decent night's sleep can leave you feeling grumpy and restless, and may stifle weight loss efforts. Dr Siobhan Banks has been researching sleep and weight loss at the University of Pennsylvania School of Medicine in the US and is now a research fellow at the Centre for Sleep Research at the University of South Australia. She says research into sleep and weight is new and there is much to discover.
"We know sleep loss affects normal physiological functioning. In the short term this is not necessarily a bad thing, but when sleep loss becomes habitual the disruption of hormones and metabolism may contribute to weight gain." Dr Banks's study, undertaken at the University of Pennsylvania, studied 92 healthy adults under periods of restricted and unrestricted sleep and found that those who experienced only four hours in bed gained 1.5 kilograms during the 11-day study.
"We are still trying to work out the mechanisms and pathways involved, but I'm hoping my research will lead to a better understanding of this," Dr Banks says. Researchers at the University of Chicago say failure to get a full night's sleep can lead to weight gain or compromise your body's ability to burn fat. The researchers in the study believe that sleep restriction can lead to an increase in the hormone ghrelin, which stimulates the appetite.
Ghrelin is produced in the stomach. Too much grehlin makes us feel we're starving. Grehlin is produced while we sleep and it's thought that adequate sleep can help produce adequate grehlin. However, lack of adequate sleep upsets the balance, leading to an overstimulation of ghrelin. In research carried out at Laval University in Canada, levels of ghrelin were found to be 15 per cent higher in people who have only five hours' sleep a night, compared with those getting eight hours a night.
Leptin is the hormone that is meant to tell us when we've had enough. The Wisconsin Sleep Cohort Study found that participants with a shorter sleep cycle had reduced leptin and elevated ghrelin. The report concluded: "These differences in leptin and ghrelin are likely to increase appetite." So how much sleep is enough? Most of us chase eight hours, but how much sleep we need comes down the individual, says Dr Timothy J. Sharp, author of The Good Sleep Guide (Random House). "Don't worry about how many hours of sleep you get, but how you feel when you open your eyes in the morning," he says.
Dr Banks says: "We know there are consequences when we don't have adequate sleep, yet we give up sleep for work, social activities and responsibilities." Sleeping poorly can have a range of side effects that impact on our weight. It can lead to poor food choices, lack of energy to exercise and it can make our metabolism more overcome these issues, Dr Banks recommends factoring exercise into your daily schedule.
"Apart from relieving stress, which can trigger insomnia, exercising in the afternoon or early evening can help you fall asleep by raising body temperature a few hours before bed, allowing it to fall as you are ready for sleep later in the evening (a falling body temperature is one of the triggers for sleep). "Don't exercise too close to bedtime, as the rise in body temperature interferes with your ability to asleep."
If you have trouble falling asleep, Dr Sharp suggests introducing a "buffer zone" that involves relaxation or relaxing activities between hectic daily activity and your restful period of sleep. Getting the odd bad sleep won't impact on your weight, but if you're constantly waking feeling unrefreshed, good bedtime habits could be the best thing for you.