Depressed Patients May Sleep Better than They Think They Do

Depression and anxiety may color patients’ reports of sleep quality, researchers report in the June issue of the Journal of Clinical Psychiatry.

Jessica A. Hartmann, PhD, and colleagues recruited 211 insomnia patients from Duke Medical Center in Durham, NC, and Rush Medical Center in Chicago between January 2004 and February 2009. They divided the patients into two groups, based on the presence of comorbid psychiatric disorder. The researchers used the Beck Anxiety Inventory and the Beck Depression Inventory, which to identify patients with anxiety and/or depressive disorders.

Both groups completed the Pittsburgh Sleep Quality Index (PSQI), measuring their sleep quality over the last month. Then both groups participated in a two-week prospective sleep study during which they kept a daily sleep diary. The goal was to see how accurately patients remembered and reported their sleep quality on the PSQI.

They found the patients who didn’t have psychiatric symptoms reported their actual sleep quality fairly accurately when compared to the diary entries they kept (P < 0.001 between PSQI and SDSQ). Those with anxiety or depression, meanwhile, reported worse sleep quality on the PSQI than they did in their diary entries (P = 0.47).

“These findings confirm the notion that psychiatric patients may be more biased in their retrospective ratings than individuals without psychiatric symptoms,” the authors wrote. The index may actually be measuring sleep distress.

Sleep quality reflects factors such as total sleep time, tiredness upon waking, daytime energy levels, or functional impairment. Sleep distress is the concern and anxiety patients feel about the effects of insomnia.

Researchers and clinicians may want to use prospective sleep diaries with patients who have psychiatric disorders if they want to measure sleep quality alone, the authors suggest. The DSM-5 removed the distinction between primary insomnia and insomnia caused by psychiatric conditions, so future sleep studies may include more patients with co-morbid psychiatric conditions.

“…[T]he study by Hartmann and colleagues is important for the field of sleep and will have important implications considering recent changes in our diagnostic classification system,” Megan R. Crawford, PhD, and Jason C. Ong, PhD, of the Rush Medical Center in Chicago, wrote in an accompanying editorial.