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

Abstract

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

Figure 1

Comparisons between volunteered and dichotomous choice prompts for the causes of nightly awakenings. *P < 0.05. P value determined using McNemar test; however, McNemar test cannot be used when one comparison value is equal to zero.

Figure 2

Total scored awakenings categorized by causal factor. Leg jerk: awakening preceded by independent leg jerk without any other observable precipitating event. Spontaneous: awakening without any clear-cut cause. Lab-induced: awakenings caused by entrance of PSG technician into bedroom (fix cannula, reattach lead, reposition pulse-oximeter). Respiratory-related: awakening preceded by a clear-cut breathing event (respiratory effort-related arousals, hypopnea, apnea) and without any other observable precipitating event.