http://www.digitaljournal.com/tech-and-science/science/are-you-a-night-owl-it-s-down-to-genetics/article/490379

At you best morning, afternoon or evening? It's genetics

Posted Apr 15, 2017 by Tim Sandle
Are you sharpest in the morning or do you prefer staying up to the late hours? What makes us different might be down to genetics rather than personality, according to a new study.
Red Dwarf star Craig Charles play his funky set.
Red Dwarf star Craig Charles play his funky set.
The human body is supposed to conform to a cyclical pattern where we are awake during the day and asleep at night. This pattern is called the circadian rhythm. A circadian rhythm is a general term for any built-in biological process that displays an oscillation of about 24 hours. These 24-hour rhythms are controlled by a circadian clock and the remarkable pattern is normally seen in plants, animals, even fungi, as well as humans.
Researchers study circadian rhythms for many reasons, be this to understand how to best harmonize agricultural production to assessing the impact of shift work upon people. The scientific name for this is chronobiology. Circadian rhythms can be affected by external forces such as light and temperature (such as when a person carries out night-shift work they are often battling against the natural rhythms of their bodies).
READ MORE: Shift work sleep deprivation affects the function of the heart
While circadian rhythms are important for animal (and human health), given that circadian rhythms function to synchronize the activities in every living cell, some people appear to be perfectly happy working and playing in the opposite direction. That is they prefer working or partying at night, while most others are happy to be tucked up in bed. It appears that, New Scientist reports, that a gene variant may explain why some people prefer to stay up late and hate early mornings.
This has been found by researchers at The Rockerfeller University, New York. The scientists have pinpointed a mutated form of the CRY1 gene, which is known to play a role in the circadian clock. To investigate the mutation, the researchers studied six families in Turkey. Each member of the family carried of the CRY1 variant (39 people in total). It was found that the sleep periods of those who had the mutation shifted by 2 to 4 hours (due to a slowing down of the internal body clock). In addition, many of the subjects reported broken, irregular sleep patterns.
The research is published in the journal Cell ("Mutation of the Human Circadian Clock Gene CRY1 in Familial Delayed Sleep Phase Disorder").