Jetlag results when a temporary loss of circadian entrainment alters phase relationships among internal rhythms and between an organism and the outside world. After a large shift in the light-dark (LD) cycle, rapid recovery of entrainment minimizes the negative effects of internal circadian disorganization. There is evidence in the existing literature for an activation of the hypothalamic-pitui...

Laboratory studies have demonstrated that circadian clocks align physiology and behavior to 24-h environmental cycles. Examination of athletic performance has been used to discern the functions of these clocks in humans outside of controlled settings. Here, we examined the effects of jet lag, that is, travel that shifts the alignment of 24-h environmental cycles relative to the endogenous circa...

The timing of work and social requirements has a negative impact on performance and well-being of a significant proportion of the population in our modern society due to a phenomenon known as social jetlag. During workdays, in the early morning, late chronotypes, in particular, suffer from a combination of a nonoptimal circadian phase and sleep deprivation. Sleep inertia, a transient period of ...

It is now believed that frequent jet lag or shifts of daily rhythms caused by rotating shift work can lead to deleterious health outcomes. Indeed, many serious health problems, including breast cancer, stroke, and cardiovascular disease, have been linked to an occupational history of shift work. This has heightened interest in better understanding the biological responses to jet lag and shift w...

Jet-lag symptoms arise from temporal misalignment between the internal circadian clock and external solar time. We found that circadian rhythms of behavior (locomotor activity), clock gene expression, and body temperature immediately reentrained to phase-shifted light-dark cycles in mice lacking vasopressin receptors V1a and V1b (V1a(-/-)V1b(-/-)). Nevertheless, the behavior of V1a(-/-)V1b(-/-)...

The preceding article1 has laid the foundations for understanding the difficulties of jet-lag and shiftworker's malaise and for appreciating the various countermeasures other than chronobiotics (drugs that alter rhythms). Several approaches have met with some success. One of the major difficulties in this area is the uncontrollable nature of field studies on jet-lag and our inability to simulat...

In humans, a person's chronotype depends on environmental cues and on individual characteristics, with late chronotypes prevailing in youth. Social jetlag (SJL), the misalignment between an individual׳s biological clock and social time, is higher in late chronotypes. Strong SJL is expected in Uruguayan university students with morning class schedules and very late entertainment activities. Slee...

Frequent transmeridian flights or predominant work at night can increase cancer risk. Altered circadian rhythms also predict for poor survival in cancer patients, whereas physical destruction of the suprachiasmatic nuclei (SCN), the hypothalamic circadian pacemaker, accelerates tumor growth in mice. Here we tested the effect of functional disruption of circadian system on tumor progression in a...

The Committee to Advise on Tropical Medicine and Travel (CATMAT) provides the Public Health Agency of Canada (PHAC) with ongoing and timely medical, scientific, and public health advice relating to tropical infectious diseases and health risks associated with international travel. PHAC acknowledges that the advice and recommendations set out in this statement are based upon the best current ava...

1085 Cerebral Perfusion and Drowsiness—Poudel et al INTRODUCTION Lack of sufficient sleep can increase drowsiness and tendency to fall asleep during the day. Increased sleepiness is often manifested as response slowing, behavioral lapses,1-3 and changes in ocular and facial behaviors including droopy eyes, slow eyelid closure, head nodding, and loss of facial tone.4-6 Although total sleep depri...