A number of human studies have linked lack of sleep to weight gain – decreased insulin sensitivity and glucose tolerance as well as disruption of the natural balance between the appetite hormones grehlin and leptin have been put forward to explain this link between disrupted sleep and weight gain. In studies in rodents, researchers at Merck have now shown that T-type calcium channels regulate both sleep and body weight maintenance. Mice lacking CaV3.1 T-type calcium channels were known to have altered sleep/wake patterns and the new study showed that these mice are also resistant to weight gain induced by a high fat diet.
Writing in the Journal of Clinical Investigation, the researchers report that the knock-out mice gained significantly less weight and had less body fat than their wild-type littermates when fed a high fat diet. The resistance to weight gain of the knock-out mice could not be fully explained by reduced food intake, an overall increase in activity or increased metabolic rate. 
In further studies, a selective T-type channel antagonist, TTA-A2, was shown to prevent, and even reverse, weight gain induced by a high fat diet, and also to improve body composition to greater extent than the widely used appetite suppressant, fenfluramine. TTA-A2, when dosed either prior to the sleep phase or during the wake phase, was found to promote sleep – a result which was unexpected since the knock-out mice have increased wake time compared with wild type animals. Although the reasons for the observed differences between pharmacological antagonism and genetic knock-out remain to be fully explained, the study highlights the potential for antagonism of T-type calcium channels as a novel weight loss strategy.
The authors suggest that the benefits of T-type calcium channel antagonists may be the result of better alignment of feeding patterns and the circadian rhythm and that sleep or circadian treatments may be of particular benefit for people struggling to lose weight or maintain weight loss because of poor diet.