Melatonin and Sleep
Wednesday, January 1, 2014
can help advance or delay the sleep-wake cycle. The effect can last for six hours. When taken in the morning, it may cause fatigue and reduced reaction time, reduced vigilance and decreased vigor during the day.
When melatonin was given to people near their normal sleep time, the results differed from one study to the next. When given during the day, it promotes drowsiness and shortens sleep onset.
Of the few studies involving people with insomnia, results are inconclusive. One study of people over 50 years of age found that taking melatonin restored their sleep efficiency and improved their sleep. Other studies have demonstrated that, although sleep onset was improved, melatonin did not help people stay asleep or stay alert during the day.
Large studies are needed to demonstrate if melatonin is effective and safe for some forms of insomnia, particularly for long-term use. It may be true that melatonin is effective and safe for some types of insomnia and for children but not for other types of sleep problems. How much to take, when to take it and its effectiveness, if any, for particular disorders is only beginning to be understood.
When traveling across time zones, we need to adjust our body clocks from "home time" to the new time. The more time zones we cross, the longer it takes to reset the body clock to the new time. After arriving from a long trip, our body clocks are out of synch with the local time and we feel sleepy, alert and hungry at the wrong times. The problem is compounded by sleep loss during an overnight flight and possibly by alcohol and caffeine consumed on board. These add up to produce "jet lag." Jet lag is not "all in your head." It is a physical condition caused by the disturbance of our circadian rhythms and travel associated with sleep deprivation. An NSF survey found that about half of all business travelers experience jet lag. They report that their performance and productivity are negatively affected. The problem was worse for women than men surveyed.