Insufficient sleep has been linked to larger waistlines, up to three centimeters greater for people sleeping six hours per night compared to those getting nine hours’ sleep. It also ups risk of diabetes.
In light of the obesity epidemic and the growing number of cases of type 2 diabetes worldwide, researchers at the UK’s University of Leeds studied the impact of sleep on metabolism. Previous research has highlighted an increased risk of being overweight or obese in people who don’t get enough sleep, on average less than seven hours per night.
The study involved 1,615 adults aged 19 to 65. The scientists measured various indicators of the participants’ overall metabolic health, such as blood pressure, blood sugar, blood cholesterol and thyroid function. Participants were also asked to report how long they slept and to keep a record of food intake. According to the results, the waist measurements of people who slept on average six hours per night were three centimeters higher than participants who slept nine hours a night. They also had more chance of being overweight.
The researchers observed that levels of HDL cholesterol — so-called “good” cholesterol that protects against conditions such as disease — were lower in adults who slept less. However, the dietary habits of shorter sleepers were no less healthy, contrary to other studies, that have linked snacking and cravings for sugary or fatty foods to lack of sleep.
Stored deeper under the skin than subcutaneous fat, visceral fat builds up around organs like the liver, the pancreas and the intestines. It affects hormonal function and the body’s resistance to insulin, and can lead to inflammation, hence the associated risk of type 2 diabetes and heart disease.
Waist measurement could also predict cancer risk, according to a study published May 24 in the British Journal of Cancer. An extra 11 centimeters around the waistline increased the risk of cancer by 13%. In the case of bowel cancer, eight centimeters more fat around the hips was linked to an increased risk of 15%.
To fulfil the realistic objective of getting seven to nine hours’ sleep per night, recommendations include maximizing exposure to natural sunlight during the day, switching lie-ins for naps at the weekend, avoiding caffeine six hours before bedtime, taking exercise, skipping foods that are too high in fat or sugar in the evening or drinking alcohol.