Experiments involving rats suggest that the body’s liver, muscles, and lungs all have separate internal ‘clocks’. This could explain why jetlagged travelers or workers changing shifts patterns feel genuine aches and illnesses because of the time differences. The researchers discovered, that the clock in the brain re-set itself within just one revolution of the circadian cycle, while the clocks in the muscle and lung took six cycles to re-set, and the liver took more than 16. As well as fatigue, jetlagged people can often have upset stomachs and aching muscles. (The clock thing is the Health Mystery, but everyone knows cramped spaces, contaminated air and stale sugared peanuts are enough to give anyone stomach and muscle problems).
