Chemotherapy for breast cancer is associated with disruption of sleep-wake rhythm in women

Sep 01, 2009

A study in the Sept.1 issue of the journal Sleep shows that the sleep-wake activity rhythms of breast cancer patients are impaired during the administration of chemotherapy. Results indicate that the first cycle of chemotherapy is associated with a temporary disruption of these rhythms, while repeated administration of chemotherapy results in progressively worse and more enduring impairments.

During week one of the first cycle of chemotherapy, participants switched from low to high activity about 30 minutes later in the day and decreased their level of activity about 50 minutes earlier at night, suggesting that their days were shorter. During the first week of the fourth cycle of chemotherapy, the women increased their level of activity about 37 minutes later in the day and switched from high to low activity about 34 minutes earlier at night. Although most variables returned to baseline levels in the second and third weeks of the first cycle of chemotherapy, circadian impairments were maintained on several variables in the second and third weeks of cycle four.

Principal investigator, Sonia Ancoli-Israel, PhD, professor of at the University of California San Diego, said that the findings were not surprising. Sleep disturbances are common in cancer patients, with 30 percent to 50 percent reporting symptoms of insomnia. Previous studies also have shown that both sleep and get worse with chemotherapy, so it was expected that would deteriorate.

"Results of this study suggest that our biological clocks are affected by chemotherapy. Our , or circadian rhythm (24-hour cycles) help keep our bodies in sync with the
Environment," said Ancoli-Israel. "During chemotherapy, our biological clock gets out of sync, especially after the first cycle of treatment. The clock seems to regulate itself after only one cycle, but with repeated administration of chemotherapy, it becomes more difficult for the biological clock to readjust."

The study involved 95 women with a mean age of 50.72 years who were scheduled to receive neoadjuvant or adjuvant anthracycline-based chemotherapy for stage I-III .

Participants wore a wrist actigraph for 72 consecutive hours at baseline (pre-chemotherapy), as well as during the first, second and third weeks of both cycle one and cycle four of chemotherapy. At each assessment they also completed a sleep log to record their bedtime, wake time and napping periods. Sleep-wake circadian activity variables were computed based on actigraphic data. Of the participants, 75 percent were Caucasian, 69 percent were married, 77 percent had at least some college education, and 73 percent reported an annual income of more than $30,000.

Compared with baseline measures, all circadian rhythm variables except acrophase (the time of day of the peak of the curve) were significantly impaired during the first week of both the first and fourth chemotherapy cycles. These circadian rhythm variables included amplitude (height of the circadian rhythm), mesor (the mean of the rhythm), up-mesor (time of day when activity was switched from low to high), and down-mesor (time of day when activity switched from high to low).

According to the study, further research must be conducted in order to better understand the mechanisms through which chemotherapy may contribute to impairments in sleep-wake activity. Potential mechanisms include psychological factors (i.e. anxiety and depression) and behavioral factors (increased daytime napping), as well as physiological factors and physical symptoms, such as decreased levels of estrogen, impaired cortisol responses and inflammation.

The authors state that it is important to screen more routinely for sleep and circadian disruptions in breast cancer patients undergoing and to offer appropriate management, such as cognitive behavioral therapy or bright light therapy, in order to prevent sleep disturbances from becoming chronic.

Source: American Academy of Sleep Medicine (news : web)

Explore further: One common genetic variant and bacteria help dictate inflammation, antitumor activity

add to favorites email to friend print save as pdf

Related Stories

Molecular partnership controls daily rhythms, body metabolism

Nov 26, 2008

A research team led by Mitchell Lazar, MD, PhD, Director of the Institute for Diabetes, Obesity, and Metabolism at the University of Pennsylvania School of Medicine, has discovered a key molecular partnership that coordinates ...

Lack of fragile X and related gene fractures sleep

Jun 26, 2008

Lack of both the fragile X syndrome gene and one that is related could account for sleep problems associated with the disorder, which is the common cause of inherited mental impairment, said a consortium of researchers led ...

Rotating shift workers have lower levels of serotonin

Aug 01, 2007

People who work rotating shifts have significantly lower levels of serotonin, a hormone and neurotransmitter in the central nervous system believed to play an important role in the regulation of sleep, according to a study ...

Recommended for you

Putting the brakes on cancer

8 hours ago

A study led by the University of Dundee, in collaboration with researchers at our University, has uncovered an important role played by a tumour suppressor gene, helping scientists to better understand how ...

Peanut component linked to cancer spread

9 hours ago

Scientists at the University of Liverpool have found that a component of peanuts could encourage the spread and survival of cancer cells in the body.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

E_L_Earnhardt
not rated yet Sep 01, 2009
ADDING ANYTHING IS UNSCIENTIFIC TREATMENT FOR THE PROBLEMS OF ACCELERATED MITOSIS!, ("Cancer")! If you want to DECELERATE the mitosis process DRAIN OFF EXCESS ELECTRONS! Mitochondria can then regain
control, and the cell can resume normal function!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.