No abstract

These findings show that better sleep efficiency and less sleep disruption are significant independent prognostic factors in women with advanced breast cancer. Further research is needed to determine whether treating sleep disruption with cognitive behavioral and/or pharmacologic therapy could improve survival in women with advanced breast cancer.

We examined sleeping problems in women with metastatic breast cancer in relation to depression, social support, and salivary cortisol. Ninety-seven women with metastatic breast cancer were drawn from a larger study on the effects of group therapy on quality of life and survival. This study is based on the baseline assessments conducted prior to randomization into treatment conditions. Sleep, depression symptoms, and social support were assessed by self-reporting. Cortisol was assessed from saliva samples taken over a 3-day period. Medical status and demographic characteristics were also examined in relation to each sleep variable in multiple regression analysis. Most women (63%) reported one or more types of sleep disturbance and 37% reported using sleeping pills in the previous 30 days. Problems with falling to sleep were significantly related to greater pain and depressive symptoms. Problems of waking during the night were significantly associated with greater depression and less education. Problems in waking/getting up were significantly associated with greater depressive symptoms and less social support. Sleepiness during the day was not significantly related to the variables in the regression model. Fewer hours of sleep were significantly associated with metastases to the bone, higher depressive symptoms, and more social support. Women who reported sleeping 9 or more hours per night, compared to those who reported a moderate amount of sleep (6.5-8.5 hours), had significantly lower 9 p.m. cortisol levels. Use of sleeping pills was more frequent among women reporting greater pain and depressive symptoms. These results suggest that women with metastatic breast cancer who are at higher risk for having sleeping problems are those who are less educated, in pain, depressed, have bony metastases, or lack social support.

Disruption of circadian rhythms, which frequently occurs during night shift work, may be associated with cancer progression. The effect of chronotype (preference for behaviors such as sleep, work, or exercise to occur at particular times of day, with an associated difference in circadian physiology) and alignment of bedtime (preferred vs. habitual), however, have not yet been studied in the context of cancer progression in women with breast cancer. Chronotype and alignment of actual bedtime with preferred chronotype were examined using the Morningness–Eveningness Scale (MEQ) and sleep-wake log among 85 women with metastatic breast cancer. Their association with disease-free interval (DFI) was retrospectively examined using the Cox proportional hazards model. Median DFI was 81.9 months for women with aligned bedtimes (“going to bed at preferred bedtime”) (n=72), and 46.9 months for women with misaligned bedtimes (“going to bed later or earlier than the preferred bedtime”) (n=13) (log rank p=0.001). In a multivariate Cox proportional hazard model, after controlling for other significant predictors of DFI, including chronotype (morning type/longer DFI; HR=0.539, 95% CI=0.320–0.906, p=0.021), estrogen receptor (ER) status at initial diagnosis (negative/shorter DFI; HR=2.169, 95% CI=1.124–4.187, p=0.028) and level of natural-killer cell count (lower levels/shorter DFI; HR=1.641, 95% CI=1.000–2.695, p=0.050), misaligned bedtimes was associated with shorter DFI, compared to aligned bedtimes (HR=3.180, 95% CI=1.327–7.616, p=0.018). Our data indicate that a misalignment of bedtime on a daily basis, an indication of circadian disruption, is associated with more rapid breast cancer progression as measured by DFI. Considering the limitations of small sample size and study design, a prospective study with a larger sample is necessary to explore their causal relationship and underlying mechanisms.

No abstract