Its all in your hair , whether you are an early riser or choose to wake up late, a new insight has revealed.
According to National Geographic News, that's because the genes that regulate our body clocks can be found in hair-follicle cells, researchers have discovered.
Makoto Akashi, of the Research Institute for Time Studies at Yamaguchi University in Japan, and colleagues conducted the study on hair samples of four subjects who followed a strict schedule as per their preferences - waking up early or late and eating, among other lifestyle choices.
This indicates that the brain "turns on" the genes at different times of the morning in different people.
The study may help researchers understand body-clock disorders a little better than before.
Disorders of the body clock have been implicated in high blood pressure, diabetes-even cancer.
The follicle test could be used to develop "working conditions that do not disturb clock function" by building in enough time to adjust, the authors wrote.
"I hope that our method will be used for regular health checks in schools and companies to keep healthy clocks," Akashi said.
The study appears August 24 in the journal Proceedings of the National Academy of Sciences.