The length of the endogenous period of the human circadian clock (tau) is slightly greater than 24 hours. There are individual differences in tau, which influence the phase angle of entrainment to the light/dark (LD) cycle, and in doing so contribute to morningness-eveningness. We have recently reported that tau measured in subjects living on an ultradian LD cycle averaged 24.2 hours, and is si...

CONTEXT Prolonged transmeridian air travel can impart a physical and emotional burden on athletes in jet lag and travel fatigue. Jet lag may negatively affect the performance of athletes. STUDY TYPE Descriptive review. EVIDENCE ACQUISITION A Medline search for articles relating to jet lag was performed (1990-present), as was a search relating to jet lag and athletes (1983-January, 2012). Th...

The number of travellers undertaking long-distance flights has continued to increase. Such flights are associated with travel fatigue and jet lag, the symptoms of which are considered here, along with their similarities, differences, and causes. Difficulties with jet lag because of sleep loss and decreased performance are emphasised. Since jet lag is caused mainly by inappropriate timing of the...

Arousal is largely controlled by the ascending arousal system of the hypothalamus and brainstem, which projects to the corticothalamic system responsible for electroencephalographic (EEG) signatures of sleep. Quantitative physiologically based modelling of brainstem dynamics theory is described here, using realistic parameters, and links to EEG are outlined. Verification against a wide range of...

BACKGROUND Melatonin has long been used as an over-thecounter aid to assist with hastening sleep onset and treating symptoms of jet lag, with jet lag being the most common application. The effects of jet lag are greater based on an increase in the number of time zones travelled and when experiencing eastbound travel. Jet lag may have varying effects on an individual, and is associated with cogn...

Jet lag and shift lag have similar physiological consequences, but shift lag is a more complex problem. The most severe desynchronization may be experienced by airline personnel making transmeridian flights. Coping strategies for eastward and westward travelers and for shiftworkers are recommended, as are interventions involving melatonin.

Age-related changes in the mammalian circadian system may be associated with a decline in circulating melatonin levels. Using 'jet lag' paradigms involving abrupt shifts in the light-dark cycle, we showed that a melatonin agonist, S-20098, accelerated by approximately 25% resynchronization of the circadian activity rhythm in old hamsters to the new light-dark cycle. It suggests the usefulness o...

OBJECTIVE To determine whether doses of the pineal hormone melatonin alleviate jet lag. DESIGN Double blind, placebo controlled crossover trial. SETTING Long haul return flights from Auckland, New Zealand, to London and back. SUBJECTS Twenty volunteers with experience of transcontinental flights (eight women and 12 men aged 28 to 68). INTERVENTIONS Melatonin (or placebo) 5 mg three days...

The need for athletes to travel long distances has spurred investigation into the effect of air travel across multiple time zones on athletic performance. Rapid eastward or westward travel may negatively affect the body in many ways; therefore, strategies should be employed to minimise these effects which may hamper athletic performance. In this review, the fundamentals of circadian rhythm disr...