In 2017, a group of American geneticists were awarded the Nobel Prize for Physiology or Medicine for their discoveries explaining how not only humans but also plants and animals, adjust their lives to the rotation of the earth. While many of us are aware that an internal body clock helps govern our daily patterns, few of us probably understand how it actually works. Nor would many fully appreciate the essential role our circadian rhythms play in regulating the body's essential functions, including behaviour, hormone levels, sleep periods and body temperature.

Working with fruit flies, these scientists were able to isolate the previously identified period gene, responsible for maintaining the body clock. By isolating this gene they were able to determine that PER, the protein associated with the period gene, amassed during the night and diminished during the day following the 24 hour circadian pattern. Further investigation revealed a second gene, timeless, produced a protein TIM that bonds with PER to regulate the production of PER, essentially forming the on/off switch to the body clock. As this did still not explain how the switch was regulated, the geneticists continued their search, establishing the presence of a third gene. The doubletime gene with its protein DBT, were found to slow the production of the PER protein, offering an insight to the way the body's rhythm can be more closely aligned with day and night.

With the isolation of the period gene and their ensuing discoveries, these scientists have confirmed the importance of light on our body's natural rhythms. Considering the effect on our health and wellbeing when our body is out of kilter with our body clock (think jetlag), avoiding artificial light, particularly late in the day, can only be beneficial.

https://www.nobelprize.org/nobel_prizes/medicine/laureates/2017/press.html