Body-clock drug could lead to cure for jet lag

Scientists tested drugs on mice that reduced the activity of a key part of the clock mechanism in the body.

By inhibiting an enzyme called casein kinase 1, they were able to restart the clock when it had stopped ticking altogether.

Many biological activities, from sleep in mammals to flowering in plants, are governed by the circadian clock - an internal timing mechanism tied to day and night cycles.

Upset circadian rhythms also play a role in certain psychiatric illnesses such as bipolar disorder.

Changes in casein kinase 1 activity adjust the "ticking" of the clock, so that it switches to a different time period. A 24-hour clock may become a 25-hour clock, for instance.

"Consider that if your body suddenly starts working on a 23-hour or 25-hour clock, many of your natural processes, such as sleeping and waking, could soon become out of step with day and night," said study leader Professor Andrew Loudon.

The effects of an out-of-kilter body clock are most commonly experienced by people who fly through time zones and by night-shift workers.

Symptoms include fatigue, irritability, clumsiness, indigestion, disturbed bowels, memory loss and difficulty concentrating.

The scientists used two unnamed molecules, known as PF-4800567 and PF-670462, in their experiments.

They found that both in live mice and in cells and tissue samples, the drugs were able to "kick-start" circadian rhythms by inhibiting casein kinase 1.

The research was carried out by collaborating teams from the University of Manchester, the Medical Research Council and the drug company Pfizer.