Excessive daytime sleepiness in cancer patients

Excessive daytime sleepiness (EDS) is commonly reported in patients with cancer, and it is also a cardinal feature of central disorders of hypersomnolence. Multiple sleep latency testing (MSLT) is used for objective assessment.

A retrospective review of patients with cancer history who underwent formal sleep evaluation and MSLT from 2006 to 2019 was performed. Clinical characteristics, sleep-related history, and polysomnographic data were reviewed.

Of 16 patients with cancer history, 9 were women (56%) and median age was 49. Cancer diagnoses included 4 central nervous system, 3 breast, 1 lymphoma, and 9 other solid malignancies, and 31% were undergoing active treatment. Comorbid conditions included depression, obstructive sleep apnea, and cancer-related fatigue. Daytime fatigue (94%), daily naps (81%), and EDS (69%) were the most common symptoms. Hypnopompic and hypnogogic hallucinations, sleep paralysis, sleep attacks, and cataplexy were present in a few. Epworth Sleepiness Scale scores were consistent with EDS in 88%, and mean sleep latency was less than 8 min in 69%. Only 31% had more than 2 sleep-onset REM periods. MSLT supported diagnoses of central disorders of hypersomnolence in 5 patients (4 narcolepsy, 1 idiopathic hypersomnia); 5 hypersomnia due to a medical disorder, psychiatric condition, or medication; and 6 with normal results. Pharmacotherapy was prescribed in 5 patients.

EDS in patients with cancer may be multifactorial, but persistent symptoms may indicate an underlying disorder of hypersomnolence. Sleep referral and polysomnography to exclude other sleep disorders may be indicated. MSLT can help confirm the diagnosis. In those with normal MSLT, further evaluation for mood disorder should be considered.