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Daylight Savings and Your Circadian Rhythms

 
By: NCSF  on:  Mar 13 2012
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Like it or not, most residents of the United States find themselves having to “spring forward” an hour come March. While clocks on the wall are easily changed, the biological clocks that control our circadian rhythms do not adjust as easily. Research suggests these rhythms, which generally take about 24 hours to reset, may take even more time than usual when we lose that hour versus the “fall back” of autumn.

Our sleep patterns are affected by circadian rhythms, which also cause jet lag and trigger the grogginess associated with the time change. These rhythms influence hormonal production, hunger, cell regeneration, and body temperature; they are also linked to chronic and acute disorders such as obesity, depression, and seasonal affective disorder.

Circadian rhythms involve the interaction of molecules in numerous cells throughout the body. The hypothalamus is responsible for multiple activities, including the regulation of dynamic metabolic and neurochemical activity. It also regulates body rhythms via a group of nerve cells called the suprachiasmatic nucleus (SCN), which is located above the optic nerve and relays information from the eyes to the brain. The hypothalamus also collects information from hormones and other chemical signals, including the expression of numerous genes and associated proteins. One such protein, aptly named CLOCK, functions with an antagonist metabolic protein called SIRT1, which senses energy use in cells. Researcher at the University of California, Irvine, found that when the CLOCK-SIRT1 equilibrium is maintained, our rhythms cause normal homeostatic conditions. When we experience an event such as a time change, this equilibrium is lost; our sleep patterns are disrupted and we feel hungrier. For example, consistently sleeping less than 6 hours a night causes an increase in hunger proteins. If the proteins remain chronically unbalanced, the related increase in caloric intake can contribute to obesity.

Traveling through multiple time zones can also have a negative effect on our circadian rhythms. The changes in time offset the body’s clock during air travel, as do natural triggers such as light and darkness. For instance, when the body is expecting to experience sunlight and instead experiences darkness, we may feel disoriented or disconnected. Lower levels of light cause the SCN to direct the brain to produce more melatonin. Melatonin triggers a sleep response, and we may feel drowsy at inappropriate times.

However, while the hypothalamus is subject to disruption, it is also able to adjust the circadian rhythms to the new environment. Research suggests it may take 24 hours of recovery for each hour difference. Traveling across multiple time zones, or even full-day zones (as seen during international flights or when traveling west to east), can require days of recovery to regain circadian rhythm normalcy. Unfortunately, for most people, return travel disrupts their circadian rhythms almost as soon as they feel normal again.

Time for Treatment

There are some common treatment recommendations for travelers or those unable to bounce back quickly from a time change. The first step is to get in sync with the time of the environment. Instead of going to sleep when you arrive at your destination, go for a walk or do some sight-seeing. Get up at your usual hour and keep to your usual routine as much as possible. Second, carbohydrate balance and hydration improve the responsiveness of the reset process. Consume fruits and vegetables, and avoid alcohol, excess caffeine, and fatty foods. Third, moderately-high intensity activity is believed to reduce the duration of disruption. The dramatic effects of physiological disruption associated with intense exercise may cause a reset during recovery. Each person’s clock is different (hence morning larks versus night owls), and responses to environmental changes may vary, but trying different techniques or practicing a combination will generally prove successful.

 
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