Owl or lark? Morning people have a lower risk of breast cancer

Study: Early risers have a lower risk of breast cancer

A new study has shown that women who belong to the so-called morning types (larks), have a lower risk of breast cancer. The researchers also found evidence of a causal link between prolonged sleep and breast cancer.

Risk factors for breast cancer

Breast cancer, also called breast cancer, is the most common malignant tumor in women. In Germany alone, up to 70,000 new cases are counted each year. As with most other cancers, the root causes are unknown. However, some risk factors for breast cancer are known. Among other things, the risk increases with age, family history, genetic changes and smoking. Also, a lot of body fat and lack of sleep are associated with an increased risk of breast cancer. That there is an association between sleep and breast cancer risk has also been shown in a recent study by British scientists.

Researchers have found that women who belong to the so-called morning types, have a lower risk of breast cancer than evening types. (Image: WavebreakMediaMicro / fotolia.com)

"Larks" have a lower risk of breast cancer than "owls"

Day or night human: There are so-called morning types (larks), which wake up early and are fast performing, and evening types (owls), which are awake and active in the evening.

The former apparently have a health benefit. Because, as shown in a study by the University of Bristol (UK), women who are "larks" have a lower risk of developing breast cancer.

The study, with data from over 400,000 women investigating whether the way people sleep can contribute to breast cancer, also found evidence of a causal link between prolonged sleep and breast cancer.

The results of the study were published on the preprint server "BioRxiv".

Increased risk due to longer sleep

In order to arrive at their results, Dr. Rebecca Richmond from the University of Bristol and her colleagues reported data from 180,215 women enrolled in the UK Biobank Project and 228,951 women who participated in a breast cancer study conducted by the International Breast Cancer Association Consortium (BCAC).

The scientists found that the breast cancer risk of the "lark" women in the BCAC study was 40 percent lower than that of the "owls".

It was also found that women who slept longer than the recommended seven to eight hours had a higher risk for the disease.

The analysis of UK biobank women data showed similar results. For morning types, breast cancer risk was reduced by 48 percent.

Effects of night shift work

"We would like to continue working to investigate the mechanisms that underlie these outcomes, as the estimates are based on morning or evening preference issues rather than whether people will get up sooner or later in the day," said Drs. Richmond in a message.

In other words, the risk of breast cancer may not be altered by a change in habits, it could be more complex.

"However, the results of a morning breast cancer risk protective effect in our study are consistent with previous research that highlights the role of night shift work and exposure to" light at night "as risk factors for breast cancer," said the study author.

Consequences for influencing sleep habits

The researchers believe that their results impact policymakers and employers.

"These results have potential policy implications for influencing the sleep habits of the population to improve health and reduce the risk of breast cancer in women," said Drs. Richmond.

The scientists are now planning to investigate the mechanisms underlying the effects of various sleep characteristics on breast cancer risk.

"We want to use genetic data from large populations to better understand how disrupting the natural body clock can contribute to breast cancer risk," said the researcher.

Cliona Clare Kirwan from the University of Manchester, who was not involved in this research, said, "We already know that night shift work is associated with a deterioration of mental and physical health. This study provides further evidence that disturbed sleep patterns may play a role in cancer development. "(Ad)