New study suggests that women who are morning people are are at lower risks of breast cancer.
For their research they used health data 80,216 women from the UK Biobank and 228,951 women from the Breast Cancer Association Consortium.
They found evidence that morning preference people have a protective effect on breast cancer risks. The report also found evidence women who sleep more than 7-8 hours have adverse effect on breast cancer risks.
Breast cancer develops from breast tissue. Breast cancer grows when abnormal cells grow out of control, enters into nearby cells, and spreads to other extremities.
According to National Cancer Institute (NCI) there were 3.5 million women diagnosed with cancer in 2016. The NCI also found that there were 13% of women in U.S who were diagnosed with breast cancer once in their lives.
In the new study researchers carried out two analysis. They performed multivariable regression on UK biobank data to find association between breast cancer and what each participants reported morning or evening preference, insomnia symptoms, and sleep duration in one analysis.
In the second analysis they used generic information of insomnia, sleep duration to find the association between these and breast cancer.
The multivariable regression on UK biobank data found that women with a morning preference have 1% lower risks of cancer than women with evening preference.
The first analysis found less association between sleep duration and insomnia symptoms.
The researchers prefer to use MR analysis data as their data came from observational studies, which are studies that people track over time. Such studies found association between variables, they are not able to prove one variable causes another.
Caroline Relton, professor at the University of Bristol in U.k and coauthor described that sleep has consequences on overall health.
The main lifestyle factors that are associated with cancer are alcohol intake, BMI, and obesity, according to Relton.
Sleep can be a risk factor for breast cancer, but is not large enough as another factors such as alcohol, or BMI- according to lead author Dr. Rebecca Richmond.