Psychological treatment of reported sleep disorder in adults with intellectual disability using a multiple baseline design
Gunning MJ., Espie CA.
Background. The literature on sleep disturbance in adults with intellectual disability (ID) is sparse. Although prevalence rates for sleep disorders appear similar to those of non-disabled populations, previous treatment studies have largely been comprised of uncontrolled cases. Therefore, the present study adopted a single-case experimental methodology to evaluate behavioural sleep intervention. Methods. A screening questionnaire was posted to 384 adults with ID and the sleep pattern of respondents with possible sleep disorders was further assessed using a structured diagnostic schedule. From the sleep-disordered subgroup, 12 participants were selected for a 4-week behavioural sleep intervention that was evaluated using randomly allocated, multiple-baseline, across-subjects designs and within-subject interrupted time series analyses (ITSAs). Results. A total of 155 adults with ID (83 females and 72 males; mean age = 32 years, SD = 16.5 years), or their carers, completed the questionnaire (return rate = 40%). The application of sleep diagnostic criteria revealed that 17% had clinically significant difficulty getting to sleep and 11% had difficulty remaining asleep. Nine out of the 12 participants recruited for the intervention completed all the experimental phases, thus providing three sets of three multiple-baseline designs. Visual inspection of within- and between-subject effects suggested beneficial treatment-specific effects across a range of target variables. The ITSA confirmed significant effects (P < 0.05) or trends (P < 0.10) for six out of the nine participants. Conclusions. Behavioural sleep management may improve sleep pattern or sleep-related functioning in the majority of adults with ID who have significant sleep problems. The single-case methodology is helpful in addressing the heterogeneity of individual presentation, although clinical trial methodology is required to confirm these findings on a larger scale.