Journal of Intellectual Disability Research 701
doi: 10.1111/j.1365-2788.2006.00830.x
pp – Blackwell Publishing LtdOxford, UKJIRJournal of Intellectual Disability Research-© The Authors. Journal compilation © Blackwell Publishing Ltd10701710Original ArticleSleep–wake
cycle in intellectual disability and
autismD. J. Hare et al.
Objective investigation of the sleep–wake cycle in adults with intellectual disabilities and autistic spectrum disorders D. J. Hare, S. Jones & K. Evershed Academic Division of Clinical Psychology, School of Psychological Sciences, University of Manchester, Manchester, UK
Abstract Background Disturbances in circadian rhythm functioning, as manifest in abnormal sleep–wake cycles, have been postulated to be present in people with autistic spectrum disorders (ASDs). To date, research into the sleep–wake cycle in people with ASDs has been primarily dependant on third-party data collection. Method The utilization of non-invasive objective recording technologies such as actigraphy permits investigation of both sleep and circadian rhythm functioning in people with ASDs, together with the collection of data on daytime activity. Results Data were collected from 31 participants with intellectual disabilities living in supported community-based residential provision aged between 20 and 58 years, of whom 14 had an ASD. Analysis indicated that there were no significant differences in sleep patterns and circadian rhythm function between those participants with an ASD and those without.
Correspondence: Dr Dougal Julian Hare, Academic Division of Clinical Psychology, School of Psychological Sciences, University of Manchester, Education and Research Building, Wythenshawe Hospital, Manchester M LT, UK (e-mail:
[email protected]).
Conclusions The mean scores of the participants as a whole indicated abnormalities in the two key circadian rhythm parameters of interdaily stability and intradaily variability. The implications of these findings for both clinical practice and theory are discussed. Keywords actigraphy, autistic spectrum disorders, intellectual disabilities, sleep
Introduction The sleep–wake cycle has been an important focus for research into a range of developmental and psychiatric conditions and is itself one of a number of circadian rhythms (i.e. biological rhythms with a frequency of one cycle in ± h). Circadian rhythms include body temperature, allergy susceptibility, hormone production and general activity, as well as the pattern of sleeping and waking. Disturbances in circadian functioning, because of both endogenous and exogenous factors, have been discussed in the context of sleep disorders in people with intellectual disabilities (IDs) (Espie & Tweedie ; Poindexter & Bihm ; Espie et al. ). Disturbances in circadian rhythms, again, primarily in the form of sleep disorders, have also been noted in people with autistic spectrum disorders (ASDs), but to date there have
© The Authors. Journal Compilation © Blackwell Publishing Ltd
Journal of Intellectual Disability Research 702 D. J. Hare et al. • Sleep–wake cycle in intellectual disability and autism
only been a small number of published research and clinical studies on this topic (Stores & Wiggs , ; Diomedi et al. ; Elia et al. ; Williams et al. ). The research to date has focussed primarily on young children with ASD and has examined both specific sleep disorders (difficulty in falling asleep, frequent night-time waking and early wakening) (Hoshino et al. ; Taira et al. ; Johnson ; Hering et al. ; Schreck & Mulick ) and disturbances of sleep–wake rhythms (Inuama ; Takase et al. ; Richdale & Prior ; Patzold et al. ). A welcome development has been the study by Wiggs & Stores () that investigated both sleep patterns and underlying sleep disorders in children with ASD. Such a widespread occurrence of sleep disturbance has been considered to be relatively specific to children with ASD, compared with both typically developing children and children with ID without ASD (Richdale & Prior ). For comparison, sleep problems, such as night-time waking, in typically developing children are described as common up to years of age, but then show a decline from a prevalence rate of % to just % by the age of years (Richman et al. ). By comparison, Richdale & Prior’s () studies indicated that up to –% of children with autism exhibit such sleep disorders by the age of years and that such disturbance was likely to be severe, particularly when the children concerned also had more severe ID (Hoshino et al. ). Reduced daytime activity levels, indicative of sleep–wake cycle dysfunction, have also been associated both directly and indirectly with the maintenance of specific forms of challenging behaviour in people with ASD and ID, as well as in typically developing children (e.g. Zuckerman et al. ; Elliott et al. ; Piazza et al. ; Wiggs & Stores , ; O’Reilly & Lancioni ). The research findings on the sleep–wake patterns of people with autism and/or ID have been discussed with respect to both endogenous neurobiological mechanisms of sleeping and waking and exogenous environmental factors (zeitgebers) which modulate these processes (Borbély & Achermann ), primarily focussing on the role of melatonin (Arendt ). Several studies have indicated deficiencies in melatonin production (Panksepp et al. ) and an abnormal elevation of daytime melatonin levels in children and young adults with autism (Richdale & Prior
; Ritvo et al. ; Nir ). Melatonin has also been used, with varying degrees of success, to treat severe sleep disorders in a children with developmental disabilities (Jan et al. ; Camfield et al. ), but to date there are no studies of its efficacy specifically with children or adults with ASDs. In addition, dysfunction in non-environmentally modulated (i.e. ‘free running’) chronobiological processes has been postulated to be causal with regard to the development and presentation of many aspects of ASDs and developmental language disorders (Boucher ). Boucher proposes that impairments in the functioning of the various temporal processors (biological clocks) (operating between milliseconds up to the h circadian rhythm) may be the fundamental cause of the key impairments in autism. The h clock is considered to be primary in the establishment of other shorter time-period clocks. There is currently little of empirical data to directly support such a model, but abnormal sleep–wake cycles and impaired circadian rhythms have been implicated as an important causal mechanism (possibly via the serotinergic system and brainstem development) in the development of the anxiety and restlessness often associated with ASDs (Segawa et al. ; Nomura et al. ). Moreover, Segawa et al. () reported that improvements in sleep–wake cycles in children with autism preceded improvements in other symptoms of autism such as social interaction and reactions to change. Also, the appearance of abnormal sleep–wake cycles in the first months appeared to be related to later behavioural disturbance and abnormal cerebral lateralization development. However, Stores & Wiggs () urge caution in drawing simple causal interpretations from the association between sleep disturbances and autism, given that other medical and developmental conditions may often be present. A further note of caution is sounded by Hering et al. (), who investigated sleep functioning in children with ASD aged between and years using objective data obtained via actigraphy (see below). This study found little difference between this group of children and a matched group of typically developing children. Interestingly, although the children studied by Hering et al. were described by their parents as having sleep disorders, including early waking, sleeping less and frequently waking at night, the only ‘disorder’ indicated by the objective data from the actigraph was early waking (sleep offset).
© The Authors. Journal Compilation © Blackwell Publishing Ltd
Journal of Intellectual Disability Research 703 D. J. Hare et al. • Sleep–wake cycle in intellectual disability and autism
The research into sleep/wake and circadian functioning in people with ASDs has primarily used questionnaire and sleep diaries completed by parents in order to obtain data on sleep disorders and rhythms (e.g. Williams et al. ). However, these approaches have marked limitations, in particular the relative inaccuracy of third-party observations as compared with data from objective measures and also the increased likelihood of errors induced because of the demand characteristics of the study (e.g. Hering et al. ). In addition, there are other methodological weaknesses inherent in research to date, including a lack of normative data on sleep–wake disturbances in the population of people with ASD (both with and without IDs) as compared with people with IDs without autism and people with normal development and inconsistencies in the definition of sleep disorders (Didden & Sigafoos ) In addition, studies of sleep–wake disturbances associated with ASDs have focussed exclusively on children with autism and there is a corresponding lack of knowledge about such sleep–wake disturbances in adults with ASDs. Therefore, there is both a paucity of normative data and a reliance on either invasive methodologies or ones which place a major burden on carers. Both of these methodological approaches to investigating sleep–wake disturbances in people with ASDs militate against large-scale comparative studies and the collection of data over longer time periods. The latter is important if variability or instability in the sleep–wake cycle is to be investigated as a possible prognostic and/or causative variable in the development of challenging behaviour (cf. Brylewski & Wiggs ). Actigraphy is a means of obtaining data on sleep and activity with virtually no restriction on a person’s everyday activity (Sadeh et al. ), which in turns permits both greater acceptability to more diverse and representative groups, such as people with ID and/or autism and also more sophisticated data analysis. This involves the use of actigraphs, comprising miniature accelerometers to continuously detect and record bodily movement over extended periods of up to weeks dependant on sampling rates. Data derived from actigraphy have been found to be highly correlated with data from polysomnography (JeanLouis et al. ), while obviating the inconvenience and intrusion implicit in the latter. In addition, actig-
raphy permits the objective investigation of the circadian sleep–wake cycle. To date, actigraphy has been used in two studies of sleep patterns and daytime challenging behaviour in children with severe ID (Wiggs & Stores ; Hering et al. ), one study looking specifically at children with ASD (Wiggs & Stores ) and one study examining sleep patterns in a mixed sample of young adults with ASDs (Øyane & Bjorvatn ). There are currently no studies of the sleep–wake cycle in adults with ID which have used actigraphy. Therefore, in order to systematically investigate circadian functioning in adults with ASDs, a community-based research study was conducted utilizing actigraphy to obtain ecologically valid data on sleep– wake functioning. It was hypothesized that adults with ASDs would present with () different patterns of circadian functioning (reduced relative amplitude and interdaily stability; increased intradaily variability; non- h periodicity) and () different sleep patterns (increased sleep latency and sleep fragmentation; reduced sleep efficiency and actual sleep time) compared with adults with ID but no ASDs.
Methods Participants The participants were aged over years with () a diagnosis of ID (i.e. measured IQ score of
