Previous studies have shown a link between lack of sleep and an increased risk of obesity, diabetes and cardiovascular disease. But little research has focused on sleep and bowel cancer. A new study has found that adults at risk of bowel cancer who have less than six hours of sleep a night have a higher chance of developing colorectal adenomas (growths in the bowel that can develop into cancer).
The researchers spoke to 1,240 American men and women who were scheduled for a routine colonoscopy about their sleeping patterns. A colonoscopy allows a doctor to look inside your large bowel (colon and rectum). Everyone in the study had been referred for the test by their doctor because they were over the age of 50 or had a family history of bowel cancer—that is, people considered at a higher risk of developing the disease. No one reported having any symptoms or any previous diagnosis of bowel disease or cancers.
Each person was asked about their sleeping pattern over the previous month, including how many hours of sleep they had each night, what time they went to bed, how long it took to fall asleep and if they had sleep apnoea (pauses in breathing during sleep). They were also asked about their medical history and lifestyle, for example about their diet, physical activity and if they smoked. The researchers took several body measurements in order to calculate each person’s body mass index and waist-to-hip ratio. This information was important in ruling out other potential risk factors for developing bowel cancer.
After the colonoscopies, the researchers identified 338 people who were diagnosed with at least one colorectal adenoma. After taking into account other risks associated with developing bowel cancer, they found that people who had less than six hours sleep each night had an increased risk of developing colorectal adenomas, compared with adults who had seven hours of sleep or more. However, the quality of sleep didn’t affect this risk.
The researchers conclude that increasing the number of hours sleep a person has each night may help to prevent bowel cancer.
Commenting on the research, Dr Christine Bennett, Chief Medical Officer for Bupa Australia, said:
“This study suggests that shorter duration of sleep can increase a person’s risk of developing colorectal adenomas, which can lead to bowel cancer if undetected and untreated. This study adds to the increasing evidence that reduced sleep is a risk factor for a variety of diseases. However, it’s important to consider that the study’s results only relate to people with a family history of bowel cancer and people over 50—that is, people who are at increased risk of developing bowel cancer. Also, since all of the people knew they had been referred for a colonoscopy, some of them may have felt anxious, which could impact their sleep and affect the results.”
Dr Bennett said the important thing to take away from this news is for people to be aware of the symptoms of bowel cancer and to talk to their GP if they have any concerns.
Thompson CL, Larkin EK, Patel S, et al. Short duration of sleep increases risk of colorectal adenoma. Cancer. 2011; 117(4): 841-847. doi: 10.1002/cncr.25507. Available here.