Patients with advanced-stage cancer experience very poor sleep quality and often have troubling staying awake, says Emory University researcher Kathy Parker, PhD, RN. The study provides the first comprehensive description of sleep and wake patterns of cancer patients using continuous polysomnography (PSG) data, deemed the gold standard in objective physiological measurement of sleep. It involved 114 advanced cancer patients with an average age of 51.1 years. Study patients underwent continuous sleep monitoring, or PSG, for approximately 42 hours in their home environments.
Results showed that study participants experienced severe difficulty with "state maintenance," or the ability to maintain both the sleep and waking states. Overall they had reduced quantity and quality of nocturnal sleep and episodes of sleep scattered throughout the day. Increased amounts of daytime sleep significantly and adversely affected several key parameters of nocturnal sleep quantity and quality.
However, women, Caucasians, and those who were married/partnered and had more education fared better in nocturnal sleep than other study participants. In addition, relative to breast cancer, lung cancer also may be a risk factor for poor sleep. "While it's unclear what definitively causes cancer patients to have trouble sleeping and staying awake, demographic factors and the type of cancer may be contributing factors," says Dr. Parker, Emory Nell Hodgson Woodruff School of Nursing professor, co-director of the Emory Sleep Center and study principal investigator.
Symptoms such as depression, pain and fatigue may also play a role in the disruption of sleep among this population, Dr. Parker notes. Opioids, the mainstay of treatment for pain, may have adverse effects on sleep in cancer patients by specifically suppressing deep sleep and dream sleep and altering the normal circadian rhythms, she says. Antidepressants, too, have been shown to cause either sleepiness or insomnia.
The study, funded by the National Institutes of Health/National Institute of Nursing Research (NIH/NINR), is limited by the fact that contributing variables were not included in the analyses, Dr. Parker says. Additional research is needed to determine if the sleep state instability observed in this study is related to primary sleep disorders that are common in this age group such as sleep apnea and periodic limb movement disorder.