The Benefits of Light in Our Life

The alternation of day and night rhythm of our lives has been since the dawn of time. Our body is made to live according to the circadian rhythm in which this daily and prolonged exposure to sunlight is essential for our energy, decrease in stress and sleep.

The light and the cycles of the body

The circadian rhythms (from the Latin circa meaning around and diem meaning day) indicate the alternation between days and nights. They are related to many natural physiological cycles in our body like changes in body temperature, metabolism, sleep-wake cycle or the secretion of hormones in which our main regulator is the light.

The diurnal period or the photoperiod, during which we receive the light of the day (less time and less cloudy in winter), directly affects all levels of our body. This is our internal biological clock, located in the hypothalamus, under which the influence of light (but also social), sets the tempo.

Depending on the amount of light received on the retina, it activates the hormone secretion circuit and stimulates (or not) the centres of enlightenment.

More light, more sleep and energy

We now know that sunlight triggers the secretion of cortisol, the hormone of "positive stress" that mobilizes the energies relevant to the day. Cortisol is essential to feel fit when you are awake.

In contrast, sunlight prevents the secretion of another hormone called melatonin. Involved in sleep and rest, it is undetectable by the day being at its highest level during the night. The more the day is bright and the night is black, there will be more hormonal differential (cortisol peaks during the day, melatonin peaks at night) resulting in a better quality of sleep.

The risk of lack of light

The circadian rhythm is sometimes disturbed by work schedule especially in some professions where they have "unconventional schedules" (continuous night shifts), and often by the use of new technologies (Internet, mobile, TV , etc..) that reduces our exposure to natural daylight as artificial lights are 5 to 20 times less intense than natural light, even on a cloudy day. There is a real risk of lack of light which favors the decrease of tone and drowsiness against whom it is difficult to fight.

The quality of sleep is also altered. It can be seen in workers working night shifts where they sleep during the day and their rest will be actually 30% less. This consequently exposes these workers to more incidents or accidents.

It is therefore essential to benefit in making the most of the day even during the darkest days of winter!

Sources:

http://my.clevelandclinic.org