“Anyone who has ever suffered jet lag knows firsthand that our bodies are persistent in how they keep track of time,” says Dr. Alon Avidan, director of the UCLA Sleep Disorders Center. “During jet lag, a rapid shift in the light-dark cycle temporarily disrupts one’s normal sleep-wake pattern, and our bodies become desynchronized.”

Imagine that you have just arrived in Athens after a 20-hour flight from Los Angeles via Paris. You are exhausted, your head is pounding, your eyes are shut and your 10-day trip to Greece is about to start. Your guided tour of this legendary city will take place in two hours, but you are craving sleep.

Avidan, professor and vice chair of the UCLA Department of Neurology, says you are suffering from jet-lag syndrome, a special type of circadian rhythm abnormality.

Circadian rhythms are regular and predictable cycles in sleep and wakefulness that occur during the course of a 24-hour period.  A circadian pacemaker in a special region of the brain — called the suprachiasmatic nucleus — controls circadian rhythms.  Light reaches special receptors in the retina of the eye, traveling along the optic nerve to the circadian center, causing it to “turn on” and make us alert, says Avidan.

“Darkness, or the absence of light, causes a gland to produce the substance melatonin,” says Avidan. “Melatonin is good to have around when you are trying to fall asleep, as it blocks the alerting effects of the circadian clock. This turning on and off of the circadian clock by light and melatonin, respectfully, allows us to have repetitive and synchronous circadian rhythms that are aligned to light and darkness that ultimately contributes to sleep and wakefulness.”

Read full article for list of tips on preventing jet lag.

Photo credit on home page of Link: iStock/fizkes

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