MELBOURNE, Sept. 14 (Xinhua) -- The heart rates of 70 percent of people follow weekly, quarterly or even yearly cycles, according to a study by researchers at Australia's University of Melbourne (UniMelb).
The research, published in the journal eBioMedicine, analyzed more than 900 years of smartwatch data from 623 healthy university students. The findings could improve understanding and management of neurological, psychiatric and broader health conditions, according to a UniMelb statement released on Monday.
Researchers found that most participants' heart rates followed multi-day patterns that could not be explained by season, exercise or environmental factors.
"Many people show unique rhythms in their heart rate from weekly and monthly cycles to longer rhythms such as 10 weeks or six months," said UniMelb Associate Professor Pip Karoly, who led the study.
The resting heart rate of 70 percent of participants followed a cyclic pattern over years, suggesting the body has a built-in biological pacemaker controlling heart rate over the long term, Karoly said.
Known as infradian rhythms, these patterns are involved in reproductive cycles, seasonal affective disorder -- which can cause mental health challenges in times of lower light -- and animals shedding fur or skin, the researchers said, adding that the factors governing infradian rhythms in humans remain unclear, but may involve a combination of hormonal, environmental and genetic causes.
"Interestingly though, housemates, siblings and friends had similar rhythms, suggesting people's bodies naturally sync with those they are close to," Karoly said.
The team is developing an app to track infradian rhythms in relation to neurological and psychiatric patterns and is studying the genetics of multiday rhythms. ■