Sleep is as important as nutrition and healthy physical activity for health. Sleep is necessary for cell repair, maintaining immune function, for metabolic function including appetite and glucose control and for cognitive function and mental health. Various components of sleep — duration, quality, circadian rhythm, and sleep disorders — can affect the health of people with cancer. At least half of all people with cancer have sleep problems - this may be an underestimate since many do not raise sleep concerns with their clinicians. Numerous factors may contribute to sleep problems, including pain; stress, anxiety and depression; symptoms from gut, urinary or breathing problems; medication side-effects and disrupted sleep schedules. Cancer treatment can also adversely affect sleep and also interfere with the ability to access therapy for sleep problems or maintain optimal sleep habits.
Clinical sleep disorders are very common across all ages. Among 22-year olds, 22% have a significant sleep disorder, predominantly chronic insomnia. In middle-age, this rises to over 40%, with obstructive sleep apnea (OSA) becoming more common. OSA is not more common in people with cancer, however in a large clinical cohort hypoxemia and sleep fragmentation due to OSA, (but not the apnea–hypopnea index), have been significantly associated with increased cancer-specific mortality. Insomnia is increased in people with cancer: for example , clinically significant insomnia was identified in 39% of women with stages I-IIIA breast cancer who were up to 4 years post-diagnosis. Insomnia predicts depression occurrence and relapse in those with a prior history of depression. Insomnia is also linked to reduced quality of life and mortality.
Effective, evidence-based therapy exists for sleep disorders, including cognitive behavioural therapy for insomnia (CBTi); for OSA , positive airways pressure, mandibular advancement devices and surgery; and for restless legs syndrome, medications. Increasing attention to sleep should be a focus of clinicians and patients in cancer management.