Previous research has shown that a short night’s sleep tends to make people eat more and choose foods that are higher in fat and sugar. A recent study from researchers in Sweden suggests that despite feeling tired and lacking motivation, exercise could be a means of warding off junk food cravings after a few short nights’ sleep.

Sleep plays an important role in maintaining a healthy weight. In fact, it’s an often overlooked factor in weight loss plans, and wrongly so. Previous studies have linked chronic lack of sleep to an increased risk of being overweight or obese. Sleep deprivation (less than seven hours per night), causes people to be less active and snack more, particularly on foods that are high in sugar or fat.

This latest study, from researchers at Uppsala University in Sweden, suggests that physical exercise could counteract the effects of chronic lack of sleep on the increased risk of becoming overweight or obese.

The scientists selected a group of participants of normal weights and in good physical health to study the behavior and levels of endocannabinoids, a group of chemical substances produced by the brain, which activate the neurological receptors present in the human body. These are usually elevated by short sleep duration and are responsible for compulsive behaviour towards food, particularly junk food.

In a sleep laboratory, volunteers were studied after three consecutive nights of ‘normal’ sleep (8½ hours), then after three nights with just four hours’ sleep. Meal and activity patterns were kept the same during both sessions. Blood samples were taken repeatedly to monitor endocannabinoid levels. Blood samples were also taken on the last day, both before and after a short bout of intensive exercise.

The results showed a spike in the levels of “2-arachidonoylglycerol,” the most abundant endocannabinoid in the brain, climbing about 80% higher after the nights of reduced sleep.

However, after intense 35-minute sessions of physical exercise, the study showed that this excess of endocannabinoids was halved and in some cases returned to the normal level.

This biological phenomenon is accompanied by the added stress-busting benefits of sport, which help promote sleep. In fact, even in cases of chronic sleep loss, exercise could be a means of regaining “neurological balance.”

The study is published in the journal Psychoneuroendocrinology.


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