Table 4.
Clinical studies on sleep disturbances in autism spectrum disorder in adults.
| Authors (Ref.) country |
Study design | Sample size | ASD assessment | Sleep–wake cycle assessment | Results | Major limitations |
|---|---|---|---|---|---|---|
| Godbout et al. (68) Canada |
Case–control study | 8 patients with AS (7–53 years); 8 age-/gender-matched TD subjects. | DSM-IV diagnostic criteria; ADI. | Sleep was recorded for two consecutive nights and scored according to standard methods using 20-s epochs | Patients with AS showed decreased sleep time in the first two-thirds of the night, increased number of shifts into REM sleep from a waking epoch, and all but one patient showed signs of REM sleep disruption. EEG sleep spindles were significantly decreased while K complexes and REM sleep rapid eye movements were normal. Three patients with AS, but none of the comparison participants, showed a pathological index of periodic leg movements in sleep. | Small sample size; use of medications. |
| Tani et al. (131) Helsinki, Finland |
Case–control study | 20 AS patients; 10 TD subjects. | DSM III-R diagnostic criteria; Beck Depression Inventory; Wechsler adult intelligence scale, revised version; ASSQ. | Basic Nordic Sleep Questionnaire; 6-day sleep diary. | AS adults reported frequent insomnia in all measures. | Small sample size. |
| Tani et al. (132) Helsinki, Finland |
Case–control study | 20 adults with insomnia (19.9–34.5 years); 10 age-/gender-/education-matched TD subjects. | DSM-IV-TR diagnostic criteria. | 2-nights PSG. Results of the second night recordings were included in the analysis. | AS subjects displayed a similar PSG profile compared with controls. Sleep periods were equal in both groups with a great amount of slow-wave sleep in the early part of the night. The only sign indicating decreased sleep continuity in autistic subjects was the greater proportion of wake after sleep onset. | Small sample size. |
| Tani et al. (133) Finland |
Longitudinal study | 20 adults with AS; 10 age-/sex-/intelligence-matched TD adults. | Clinical diagnosis. | Actigraphy. | People with AS did not differ from the controls regarding actigraphic sleep profiles. | Small sample size. |
| Limoges et al. (134) Canada |
Cross-sectional study | 27 adults with HFA (16–27 years); 78 TD subjects (16–30 years). | DSM-IV diagnostic criteria; ADI-R; Wechsler Adult Intelligence Scale 3ed. | Sleep habits questionnaire; Horne and Os¨tberg’s questionnaire to determine morningness–eveningness typology; laboratory sleep recordings for two consecutive nights; Achenbach Youth Self-Report scale to measure of adaptive behaviors; State–Trait Anxiety Inventory; Beck Depression Inventory; Cortisol saliva samples. | Autism group: a longer sleep latency, more frequent nocturnal awakenings, lower sleep efficiency, increased duration of stage 1 sleep, decreased non-REM sleep and slow-wave sleep, fewer stage 2 EEG sleep spindles, and a lower number of rapid eye movements during REM sleep vs. TD participants; no differences between group on the Beck Depression Inventory; trait anxiety scores on the Spielberger Anxiety Scale were higher in ASDs. Objective total sleep time correlated negatively with the Social and Communication scales of the ADI-R. The sleep structure of clinical subgroups did not differ, except fewer EEG sleep spindles in the Asperger syndrome subgroup. | Small sample size. |
| Oyane and Bjorvatn (135) Bergen, Norway |
Cross-sectional study | 9 adolescents and young adults with autistic disorder; 6 adolescents and young adults with AS; (15–25 years) | Clinical diagnosis. | Sleep questionnaire; Epworth Sleepiness Scale; 2 weeks sleep diaries; 2 weeks actigraphy. | Although the sleep questionnaires completed by parents revealed only a moderate degree of sleep problems, great sleep disturbances were recorded with actigraphy. Low sleep efficiency (below 85%) or long sleep latency (more than 30 min) have been found in 80% of the subjects. There was no early morning awakening. | Small sample size; absence of a control group. |
| Limoges et al. (136) Canada |
Case–control study | 17 adults with ASD (9 with HFA and 8 with AS); 14 TD individuals. | DSM-IV diagnostic criteria. ADI-R; a battery of nonverbal tasks was administered, in the morning after a second night of sleep in the laboratory. | PSG. | Signs of poor sleep in the autism group were significantly correlated with either normal performance (selective attention and declarative memory) or inferior performance than controls (sensory-motor and cognitive procedural memories). Both groups presented a significant negative correlation between slow-wave sleep and learning a sensory-motor procedural memory task. | Small sample size; large number of correlation. |
| Richdale et al. (106) Australia |
Case–control study | 27 adolescents with HFASD (14.2–16.8 years); 27 age-sex-matched TD; adolescents (14.4–16.6 years). | The Centre for Epidemiological Studies Depression scale (CES-D); the anxiety subscale of the Depression, Anxiety and Stress Scale (DASS-21) | 7-day sleep/wake diary; actigraphy; Sleep Habits Survey; Chronic Sleep Reduction Questionnaire to measure daytime functioning; Sleep Anticipatory Anxiety Questionnaire to measure pre-sleep arousal. | HFASD group reported significantly higher scores for depressed mood, anxiety and pre-sleep arousal vs. TD adolescents, and poorer daytime functioning. More significant correlations between sleep variables and psychopathology variables, and sleep variables and daytime functioning in the HFASD group, vs. TD group. | Small sample size. |
| Baker and Richdale (137) Australia |
Cross-sectional study | 36 adults with HFASD; 36 age-/sex-/intelligence quotient-matched TD adults. | Autism Quotient; ADOS-2. | Online questionnaire battery: PSQI; 14 days sleep diary; 14 days actigraphy. | HFASD group reported significantly more general sleep disturbances, high scores on the PSQI, long sleep onset latencies (actigraphy), and poor sleep efficiency (diary) and these results remained significant after accounting for the false discovery rate. HFASD group reported significantly shorter total sleep time, poorer refreshment scores upon waking in the morning and higher scores on the daytime dysfunction due to sleepiness subscale of the PSQI compared to the TD group. | Small sample size; use of medications. |
DSM, Diagnostic and Statistical Manual; ASD, autism spectrum disorder; AS, Asperger syndrome; HFA, high-functioning autism; ADI, Autism Diagnostic Interview; ADOS, Autism Diagnostic Observation Schedules; PSG, polysomnography; TD, typically development; REM, rapid eye movement; PSQI, Pittsburgh Sleep Quality Index.