I saw a news article on this and the researcher also pointed out that sleep deprivation leads to (I thought) changes to glucose sensitivity but she could have said glucose tolerance or insulin sensitivity. Either way, research indicates that:Scientists say they have found evidence that a lack of sleep causes changes in brain activity that lead to people feeling hungrier and craving more fattening foods.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2697035/Because sleep itself modulates glucose tolerance and homeostasis, changes in the quantity or quality of sleep may affect glucose tolerance. ... This article reviews the growing body of experimental and epidemiologic evidence linking sleep loss and sleep disturbance with alterations in glucose homeostasis.
The link to cycling is that cycling may improve both quantity and quality of sleep. Over the past 2 months or so, I have had problems sleeping properly in terms of: going to sleep late (no related to the time I go to bed), not sleeping deeply, trouble waking up and feeling tired all day. I just had 2 weeks leave and tried going to bed earlier, say between 11 and 12 but found I was awake until 2 or 3. It's frustrating being tired but not able to sleep. I was trying to find the reference to sleep and glucose and stumbled across an article in wikipedia about delayed sleep phase disorder. Naturally, I have diagnosed myself with mild delayed sleep phase disorder. According to Dr Google, I must have it
Either way, it does seem worse when the days are shorter. Linking to the above article, since I have been sleeping less and feeling more tired I have: eaten more high energy foods that I usually would (especially chocolate) and have put on about 4 kg. Maybe I should cycle more.