If you are genetically predisposed to weight gain, you may be interested in the findings of neurologist Nathaniel Watson. His research team looked at the habits of 1,088 pairs of twins in the University of Washington Twin Registry and found that those who got less sleep (less than 7 hours per night) were not only heavier, but also had less control over their weight than those who got more than 9 hours of sleep.
Watson’s team found that genes accounted for 70% of the difference in BMI in twins sleeping less than 7 hours but environment accounted for only 4%. Conversely, for twins getting more than 9 hours of sleep, genetic influences accounted for 32% of the BMI difference (less than half the effect found in the twins sleeping for less than 7 hours). for the group that slept more than 9 hours, environmental factors like diet and exercise accounted for 51% of the differences in weight.
The study based on 604 pairs of identical twins and 484 sets of fraternal twins, showed that “The less sleep you get, the more your genes contribute to how much you weigh. The more sleep you get, the less your genes determine how much you weigh.”
Previous studies have shown that not getting enough sleep is linked to weight gain but involved non-twin participants and as a result haven’t been able to tease out the effect of weight-gaining genes.
The results of the twin study suggest that shorter sleep allows for a more permissive environment for the expression of obesity related genes. The results add to the evidence that adequate sleep is crucial to maintaining a healthy weight.
This doesn’t mean that you can sleep yourself thin. But you can sleep yourself to a point were diet and activity are more important in determining your body weight than genetics.