How does Helix calculate your Circadian Rhythm result?

Circadian rhythm is an interesting biological phenomenon—it is a natural tendency of an organism to stick to a repeated cycle of wake and sleep. In humans, this cycle is roughly 24 hours long and results in an average bedtime of between 10:00pm and 12:00am, and wake time between 6:00 and 8:00am. But not everyone follows this schedule.
Some causes of a shifted circadian rhythm are due to factors you can control. Traveling across time zones, having an infant, or working a night shift can all cause someone to influence their internal clock and adopt a different circadian rhythm. But for some people, genetic factors have a natural influence the time they fall asleep and wake up.
These individuals may a hard time falling asleep before 3:00am and sometimes wake up in the late morning. People with a shifted circadian rhythm may have trouble adapting to a typical daytime work schedule.
To determine if you have a shifted circadian rhythm due to inherited genetic factors, Helix looks at a single variant, rs184039278, in the CRY1 gene. Individuals that have a C at this position are very likely to have a shifted circadian rhythm or fragmented sleep (meaning brief periods of sleep during the night supplemented by naps during the day). In contrast to other insights, your genetic results are a very good predictor of your experience.
But having a C at this position is quite rare. Only 0.2-0.3% of people have CT or CC genotypes, and it is not found equally across all populations. Only people of European or Indigenous American ancestry are likely to have a C at this position.