Cooler weather this time of year is ideally suited to a bulking phase. Not only is it easier to sleep at night, but bulky layers of clothing help camouflage the body fat that builds up as an unavoidable consequence of the increased calories you're using to fuel lean mass gains. In addition to its prominent role in muscle recovery, getting the right amount of sleep can play a role in cutting that body fat when warmer weather returns. Check out the findings of a study published in the Annals of Internal Medicine.
University of Chicago medical researchers measured the insulin response of 7 healthy lean subjects who switched from getting 8.5 hours of sleep each night to just 4.5 hours for 4 nights in a row. A glucose test showed that insulin response decreased an average of 16% and fat cell sensitivity to insulin dropped by 30%. That's important, because body fat stores and releases energy. If fat cells can't effectively respond to insulin, they might release fats into circulation. Get enough quality sleep to help muscles recover from heavy training and keep your fat cells working at peak efficiency.