Prospective assessment of nocturnal awakenings in a case series of treatment-seeking chronic insomnia patients: a pilot study of subjective and objective causes.

BACKGROUND

The cause of nocturnal awakenings in patients with chronic insomnia is rarely researched. This study prospectively assessed the etiology of nocturnal awakenings (subjectively and objectively) among patients with insomnia at a private, community-based sleep medical center.

METHODS

Twenty adult patients with chronic insomnia enrolled between April 2008 and February 2010 met diagnostic criteria for an insomnia disorder, never previously visited a sleep specialist or underwent sleep testing, and reported no classic sleep disordered breathing symptoms. Patients completed validated scales for insomnia, sleepiness, impairment, anxiety, depression, and quality of life, a qualitative interview to assess subjective reasons for awakenings, and a diagnostic sleep study to objectively assess awakenings and their precipitants.

RESULTS

Subjective and objective data showed clinically meaningful insomnia, primarily sleep maintenance insomnia. The most common self-reported reasons for awakenings were: uncertain cause (50%), nightmares (45%), nocturia (35%), bedroom distractions (20%), or pain (15%). No patient identified breathing symptoms as a cause. Objectively, 531 awakenings were observed in the total sample, and 478 (90%) were preceded by sleep breathing events (apnea, hypopnea, or respiratory effort-related event). Fifty-three awakenings were caused by other factors (independent leg jerks [7], spontaneous [14], and sleep that was laboratory-induced [32]). Thirty awakenings ≥ 5 min-a duration sufficient to predispose toward an insomnia episode-were each preceded by a breathing event.

CONCLUSIONS

Among patients with insomnia with no classic sleep breathing symptoms and therefore low probability of a sleep breathing disorder, most of their awakenings were precipitated by a medical condition (sleep disordered breathing), which contrasted sharply with their perceptions about their awakenings