To Sleep Perchance to Remain Healthy

CURE, Fall 2012, Volume 11, Issue 3

Studies show sleep deprivation may be linked to immune system health.

Sleep deprivation has been linked in the past to high blood pressure, cognitive impairment and diabetes. Now, a new study suggests it might be particularly important to cancer patients and survivors.

A study released in July from researchers in the United Kingdom and the Netherlands indicated that lack of sleep can impact the immune system in the same way as stress. The study, which appeared in the journal SLEEP, compared the number of white blood cells in 15 healthy young men who slept normally and then were subjected to severe sleep loss.

Being deprived of sleep, researchers found, impacted the granulocytes, types of white blood cells that form part of the immune system.

Martica Hall, PhD, who studies sleep and stress as a professor of psychiatry and psychology at the University of Pittsburgh, calls it a “landmark study” because of the good experimental controls that “kept participants in bed during sleep deprivation as well as consistent meal content and timing.”

“Sleep deprivation was maintained for a total of 29 hours,” says Hall, who was not involved with the study. “Its limitations are that the study was small with 15 participants and all were healthy males. That said, it is remarkable that such strong effects were observed in this ‘optimal’ cohort of healthy males.”

Hall says that while these data clearly demonstrate that sleep is an essential component of a healthy immune system, it is not yet known whether more chronic sleep restriction, such as sleeping fewer than seven hours per night over an extended period of time, would have the same effect on immune system cells including risk or progression of disease, such as cancer.

In August, researchers reported in the journal Breast Cancer Research and Treatment a possible association between sleep deprivation and a greater risk of breast cancer recurrence. The conclusions came from a study of medical records and survey results from 412 postmenopausal breast cancer patients treated at the University Hospitals Case Medical Center in Cleveland, Ohio. The women underwent the Oncotype DX test, which gave a tumor recurrence score based on expressions from 21 genes. Women were also asked at diagnosis about their sleep duration over the preceding two years.

Researchers found that those women who reported sleeping six hours or less a night had a higher recurrence score, leading them to believe that sleep could impact the carcinogenic pathways that are related to the progression of postmenopausal breast cancer. The impact on premenopausal cancer is not known.

Hall says that, while the study supports significant research that under six hours of sleep a night leads to a number of negative outcomes, gathering the information about sleep after the women were diagnosed presents a significant limitation in the study.

“On the positive side, it is a big study that supports yet another strong link between short sleep and all things bad,” Hall says, adding that sleep researchers don’t know if it’s something about being awake too much or missing something when you are asleep, but sleeping fewer than six hours is not good for the body.