In a cohort of more than 1000 persons, it was found that short sleepers had higher blood levels of ghrelin and lower levels of leptin, as well as a higher body mass index.92 Similar changes were found in an experiment in which volunteers were studied under a condition

of sleep curtailment.93 Adipocyte biology is linked to peripheral biological clocks.94 In fact, a short duration Inhibitors,research,lifescience,medical of sleep seems to modify several variables such as glucose tolerance, insulin secretion, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) towards values that favor obesity, the metabolic syndrome, and its cardiovascular complications. Jet lag Jet lag is a configuration of acute and short-lasting consequences of an selleck catalog ongoing resynchronization to

astronomical time (in order that the normal relationship between biological events and external time is regained) after Inhibitors,research,lifescience,medical rapid travel across several time zones. The circadian clock can readjust to astronomical time at a rate of about 1 hour or slightly more per day. For example, the secretion of Inhibitors,research,lifescience,medical Cortisol is normally lowest in the evening and then peaks late at night and early in the selleckchem morning, and it takes a few days for this secretion to adapt to the new schedule. Other rhythms are quicker to adjust. Thus, there is a transitory state of internal desynchronization (defined as an usual relative phase position of oscillating variables). A single night of good sleep does not suffice

to overcome jet lag biologically, although it can do Inhibitors,research,lifescience,medical so subjectively. It is postulated that if jet lag symptoms last more than a week, then the resynchronization to astronomical time might not have occurred in the faster direction, regaining the number of hours of the jet lag, but in the other direction, ie, regaining 24 hours minus the number of hours of the jet lag. Strategies to decrease the uncomfortable manifestations of jet lag have been extensively studied, and are easily consulted in the literature.95 Social jet lag When a person has a circadian clock that runs with a few hours of delay, le, Inhibitors,research,lifescience,medical a bit later than that the astronomical day/night cycle, she or he has a chronotype characterized by “eveningness,” a neologism describing difficulty falling asleep before late at night, and the associated difficulty waking up early. These persons do not have a sufficient number of hours AV-951 of sleep during week days. Roenneberg and his colleagues called this phenomenon a “misalignment of biological time to social time,”96 and they have used a specially designed questionnaire, the Munich Chrono Type Questionnaire (MCTQ) about sleep/wake habits. More than 40 000 Europeans have now answered this questionnaire. The authors have validated the existence of social jet lag as a set of recurrent and permanent consequences of having the tendency to stay awake in the evening, ie, of having a late chronotype.