Sleep time may be a modifiable risk factor for cancer, according to a recent study from Japan.
The findings reveal that sleeping 10-plus hours may increase a woman's risk of getting cancer and both men and women's risk of dying from cancer.
The researchers say their findings may help refine sleep recommendations in Japan, which currently advise working, middle-aged adults to sleep "as long as they can."
Based on the new findings, a sleep duration of 6 to 8 hours for men and 6 to 9 hours for women "may be the safest" regarding cancer incidence and mortality risk among Japanese adults, the authors conclude.
The findings were published online May 26 in the International Journal of Cancer.
In the multivariable analysis, longer sleep duration was not associated with total cancer incidence in men. In women, however, sleeping 10 or more hours vs 7 was associated with a 19% increased risk of cancer.
In addition, sleeping 10 or more hours was associated with an increased risk of dying from cancer in women.
Sleeping for 5 hours or fewer, compared with 7, was not associated with cancer incidence and mortality. However, among postmenopausal women, shorter sleep durations did increase the risk of dying from cancer.
Based on these findings, the researchers say sleep duration "may be an important variable to include in cancer incidence and mortality risk prediction models."
Int J Cancer. Published online May 26, 2022.
