Table 3.
Clinical studies on circadian rhythmicity and autism spectrum disorder in adults.
| Authors (Ref.) country |
Study design |
Sample size | ASD assessment | Sleep–wake cycle assessment | Results | Major limitations |
|---|---|---|---|---|---|---|
| Hare et al. (126) Manchester, UK |
Comparative study | 10 adults with AS; 18 TD adults. | ICD-10 or DSM-IV diagnostic criteria; ASQ. | Actigraphy; basic sleep diary | Adults with AS showed significant phase advancement in the sleep–wake cycle with longer sleep latency, lower sleep efficiency, and more fragmented sleep than TD ones. | Small sample size; participants recruited from a relatively small area; need for more closely matched participants. |
| Hare et al. (127) Manchester, UK |
Comparative study | 31 adults with ID, of whom 14 had an ASD. | IQ score; DSM IIIR/IV diagnostic criteria; ASSQ; British Picture Vocabulary Scale (BPVS) | Actigraphy; basic sleep diary | No significant differences in sleep quantity and quality between the participants depending on whether they had an ASD. | Small sample; participants recruited from a relatively small area; use of medication; people with unidentified ASD symptoms in the non-autistic group. |
| Baker and Richdale (128) Australia |
Cross-sectional study | 36 adults with ASD; 36 TD adults. | AQ; ADOS-2. | 14-day sleep–wake diary, 14-day actigraphy assessment; Composite Scale of Morningness questionnaire. | Delayed sleep–wake phase disorder, advanced sleep–wake phase disorder, and non-24-h sleep–wake rhythm disorder were present in the participants. A higher proportion of adults with ASD met criteria for a circadian rhythm sleep–wake disorder (CRSWD) compared to control adults delayed sleep–wake phase disorder. | Small sample size; no evaluation of factors that contribute to CRSWDs. |
| Goldman et al. (129) USA |
Comparative study | 28 adolescents/young adults with ASD; 13 age/sex matched TD individuals (11–26 years). | DSM-IV-TR diagnostic criteria; ADOS. | Adolescent Sleep–Wake Scale; Adolescent Sleep-Hygiene Scale; 4 weeks actigraphy; melatonin salivary collections (over 4 nights, starting at 6:00 pm and repeated every 30 min until bedtime); salivary cortisol collected immediately before bedtime and immediately upon awakening for 4 days starting on the morning after the last night of melatonin sample collection. | Compared to those with TD, adolescents/young adults with ASD had longer sleep latencies and more difficulty going to bed and falling asleep. Morning cortisol, evening cortisol, and the morning–evening difference in cortisol did not differ by diagnosis (ASD vs. TD). Dim light melatonin onsets (DLMOs) averaged across participants were not different for the ASD and TD participants. | Small sample size; emphasized HFA; participants with erratic sleep schedules, a broad age range and taking medications; not define circadian preference; psychiatric comorbidities. |
| Ballester et al. (130) Spain |
Case–control study | 41 adults with ASD and ID (<70); 51 TD adults. | DSM-5 diagnostic criteria. | Ambulatory circadian monitoring (ACM) device has three different sensors: Wrist temperature, actimeter information (motor activity and body position), light intensity; 7-day sleep–wake diary. | Circadian phase advance in the ASD group was suggested by the higher values for wrist temperature and sleep and the lower motor activity and body position during the late afternoon and the first part of the night when compared to controls. Individuals with ASD and ID presented sleep difficulties (low sleep efficiency, prolonged sleep latency and increased number and length of night awakenings), together with daily sedentary behavior, increased nocturnal activity and a consistent phase advance in circadian rhythms. |
Small sample size; ACM has not been validated in ASD to study sleep; most ASD were medicated; the group with ASD was not matched with the control group on sex, IQ, employment status, or living conditions. |
DSM, Diagnostic and Statistical Manual; TD, typically development; ID, intellectual disabilities; IQ, intelligence quotient; ICD-10, International Classification of Diseases-10; ASD, autism spectrum disorder; AS, Asperger syndrome; HFA, high-functioning autism; ADOS, Autism Diagnostic Observation Schedules; ASQ, Autism Screening Questionnaire; AQ, autism quotient.