What happens when circadian rhythms are disrupted?

Not surprisingly, when we attempt to stay awake against the schedule dictated by our circadian clock, our mental and physical performance is greatly diminished. Conditions associated with a disruption of circadian rhythms include shift work, jet lag and other circadian rhythm sleep disorders.

In jet lag, times for sleep and wakefulness dictated by the internal circadian clock do not correspond with external cues in the new time zone. The result is excessive sleepiness, poor sleep, loss of concentration, poor motor control, slowed reflexes, nausea, and irritability.

Those who perform shift work, particularly on night shifts, also may experience the effects of a disrupted circadian sleep-wake cycle; research shows that 10 to 20 percent of shift workers report falling asleep on the job. They also may suffer from diminished performance and alertness, and may be more prone to accidents. Strategies to re-align circadian rhythm, such as using melatonin help.