Dimly lit working environments : correcting your body clock is possible!

http://presse-inserm.fr/en/dimly-lit-working-environments-correcting-your-body-clock-is-possible/14196/

July 30, 2014

The system that allows our body to regulate a certain number of vital functions over a period of about 24 hours is called the body clock (or circadian rhythm). Located deep within the brain, it consists of 20,000 neurons whose pulsatile activity controls the sleep/wake cycle, body temperature, heart rate, the release of hormones, etc. The cycle determined by the internal clock lasts spontaneously between 23.5 to 24.5 hours, depending on the individual. In order to function correctly, it refers to the signals that it receives from the external world and that it interprets as indicators for the purpose of constantly resynchronising itself every 24 hours.
This is why the intake of food, physical exercise and the external temperature, for example, are said to be ‘time setters’. The most important ‘time setter’, however, is light. After inappropriate exposure to light, your entire body clock is thrown out of order with consequences for cognitive functions, sleep, alertness, memory, cardiovascular functions, etc.


For the first time, scientists have been able to study under real conditions how various types of artificial light influence the way the biological clock behaves in situations where the natural light is insufficient. For nine weeks of the polar winter (no sunlight during the day), the staff of the international polar station Concordia were alternately exposed to a standard white light and a white light enriched with blue wavelengths (a particular kind of fluorescent light that is perceived as white by the visual system). For the purposes of the study, the researchers asked the staff not to change their day-to-day habits, particularly the times they got up and went to bed.

Once a week, samples of saliva were taken in order to measure the rates of melatonin (central hormone) secreted by each of the individuals.


The details of the results show that an increase in sleep, better reactions and more motivation were observed during the ‘blue’ weeks. Moreover, while the circadian rhythm tended to shift during the ‘white’ weeks, no disturbance in rhythm was observed during the ‘blue’ weeks. In addition, the effects did not disappear with the passage of time.

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