Can You Lose Weight Through Sleeping? There are two hormones in our bodies that help control appetite: ghrelin and leptin. When you do not get enough rest, levels of ghrelin rise (this increases your hunger) but levels of leptin fall (so you don't feel full). A study has just found a significant disruption of nighttime ghrelin levels in chronic insomniacs. According to this research, this hormone imbalance leads insomniacs to experience an increase in appetite during the day, leading to weight gain over time. In addition to creating an imbalance in ghrelin and leptin, sleep deprivation causes levels of the stress hormone cortisol to rise, which increases cravings for high-carbohydrate, high-calorie 'comfort' foods. And as if that wasn't enough, the brain secretes growth hormone during the deep-sleep phase, helping the body convert fat to fuel. Without enough deep sleep, fat accumulates.... Is there a magic number of hours that we need to sleep? Apparently not, but the average adult needs about five 90-minute sleep cycles per night, so 7.5 hours seems optimal as a minimum. In the light of this new information, it would appear that current guidelines for achieving a healthy weight are now likely to become: diet, exercise and enough sleep. With Christmas & New Year coming up, will you please make sure that you get enough sleep.....?! References: S. J. Motivala, A. J. Tomiyama, M. Ziegler, S. Khandrika & M. R. Irwin. Nocturnal levels of ghrelin and leptin and sleep in chronic insomnia Psychoneuroendocrinology 2009, Volume 34, Issue 4, pages 540-545.