OBJECTIVE: To profile the daytime impact of the proposed DSM-5 insomnia disorder diagnosis, with and without mental health, physical health, or other sleep disorder comorbidities; to better understand how specific daytime symptom patterns are associated with nighttime sleep in insomnia; and to compare childhood-onset and adulthood-onset insomnia disorder with respect to daytime dysfunction.
METHOD: Data were derived from the Great British Sleep Survey (GBSS), an open-access online population survey completed by adults who had a valid postcode and were residents of the United Kingdom. The primary variables of interest were the 6 areas that, according to the proposed DSM-5 criteria, may be impacted in the daytime by insomnia disorder: energy, concentration, relationships, ability to stay awake, mood, and ability to get through work. These variables were compared for those with versus those without insomnia disorder and across 5 insomnia subtypes (difficulty initiating sleep, difficulty maintaining sleep, early morning awakening, a combination of these 3 core symptoms, or nonrestorative sleep). Clinically comorbid insomnia presentations (insomnia disorder with poor mental health/poor physical health/additional sleep disorder symptoms) and insomnia disorder of childhood versus adult onset were also evaluated.
RESULTS: A total of 11,129 participants (72% female; mean age = 39 years) completed the GBSS between March 2010 and April 2011, of whom 5,083 screened as having possible insomnia disorder. Compared with those who did not have insomnia disorder, those with insomnia disorder reported greater impairment in all areas of daytime functioning (Cohen d range, 0.68-1.30). The greatest effects reflected negative impact on energy and mood. Participants with a combination of insomnia symptoms tended to be the most impaired (Cohen d range, 0.10-0.23), whereas no consistent differences emerged between the other 4 subtypes. Finally, individuals who had both insomnia disorder and poor mental health were consistently the most impaired comorbid group (Cohen d range, 0.15-0.65), and childhood-onset insomnia disorder had greater daytime impact than adult-onset insomnia disorder (P < .05 for energy; P < .01 for mood, concentration, and getting through work).
CONCLUSIONS: The severity of daytime impact of DSM-5 insomnia disorder varies by insomnia type. This finding has implications for the evaluation and management of insomnia in clinical practice.
