Ann R. Poindexter, M.D.
Estimates of the incidence of sleep disorders in the general population vary widely, with one group estimating ranges of 20-40 percent of adults with these problems every year (Gillin & Byerley, 1990). Dement and Mitler (1993) note that as many as 80 million Americans have serious, incapacitating, often untreated, sleep problems, and La Voie (1997) reports that 47% of U.S. workers report trouble sleeping, with 2/3 of these workers thinking that insomnia has a negative impact on their job performance.
Sleep disorders are thought to play a major role in causing automobile accidents, with drowsiness being blamed for 200,00 to 400,000 automobile accidents every year (Dement & Mitler, 1993). Undiagnosed sleep-disordered breathing is usually associated with daytime sleepiness, which probably is involved with automobile and other accidents. Some studies indicate that this condition affects two to four percent of middle-aged adults (Strollo & Rogers, 1996). This condition occurs particularly frequently among men, but is also much higher than previously suspected among women (Young et al., 1993).
The frequency and importance of various kinds of sleep problems in childhood is largely unknown. Salzarulo and Chevalier reported in 1983 a survey of 218 children between two and 15 years of age, seen for pediatric or child psychiatric consultation, which assessed the frequency of sleep disorders. They found an incidence of 6.5% for night terrors, 6.5% for sleep-rocking, 9.5% for bruxism (tooth grinding), 17% for enuresis (bed-wetting), 23% for trouble falling asleep, 28% for night-waking, 31% for nightmares, and 32% for sleep walking.
Very little has been reported about the incidence of sleep problems in persons with mental retardation and other developmental disabilities. Poindexter and Bihm (1994) studied sleep patterns in a group of 103 institutionalized persons with profound mental retardation, almost all adults, and found that 38.8% had persistent patterns of short-sleep over a period of many months. Brylewski and Wiggs (1998) surveyed 205 persons, ages 18 years or over, living in community housing, with a response rate of 85.7%. Results showed problems falling asleep in 26.8%, night waking in 55.6%, parasomnias in 14%, and sleep-related breathing problems in 15%. Parasomnias reported included sleeptalking, tooth grinding, waking screaming, head banging, nightmares, and sleepwalking.
Several reports discuss the incidence of sleep disorders in children with developmental disabilities. Clements, Wing, and Dunn (1986) reported an exploratory study of a group of handicapped children which showed some degree of sleep difficulty in over a third of the group. More recently, Richdale and group (1997) assessed sleep problems in 44 children with developmental disabilities in Australia, compared with a group of 15 children without developmental disabilities. In this study children with developmental disabilities had a greater frequency of sleep problems than control children. Children with Down syndrome had higher incidence of sleep apnea than did others, and children with autism had the most severe sleep problems in the study group. Wiggs and Stores reported in 1996 results from a sleep survey of 209 children ages 5-16 years with severe learning disabilities. Forty-four percent of this sample had a current severe sleep problem most nights or every night, with an average duration of over seven years. Of the 25 children with autism in the group, 17 (68.0%) had reported sleep problems, as did seven of the twelve with cerebral palsy. After careful assessment for general daytime behavior problems, these authors concluded that the children with current sleep disturbance had significantly more daytime behavior problems than did other children.
Shibagaki and group (1985) studied development of nighttime sleep of 79 children and adolescents with mental retardation, whose ages ranged from six months to 20 years. Polygraphic recordings were carried out while the subjects were in bed, and routine sleep parameters were measured. Total sleep time and percentage of rapid-eye movement sleep decreased, and awake time tended to increase, with age, similar to the pattern seen for age-matched subjects. This group felt that their results indicated that the basic function of the sleep-waking system of children with mental retardation developed normally with age. In contrast, a study was reported from the same centers in the same year (Shibagaki, Kiyono, & Takeuchi, 1985) of sleep patterns in 23 children with cerebral palsy and mental retardation, as compared with 39 children with mental retardation without cerebral palsy. In this latter study, 11 of the children with cerebral palsy and 30 of the children with mental retardation without cerebral palsy had normal sleep patterns. Twelve other persons in the cerebral palsy group and nine of the controls had some abnormal sleep EEG patterns. After extensive analysis they concluded that brain lesion abnormalities seemed to be greater in the children with abnormal sleep patterns than in others.
Okawa and group (1987) studied chronobiologically four congenitally blind children with severe or moderate mental retardation. Three of these children showed a free-running rhythm of sleep-wake, and the fourth showed an irregular sleep-wake rhythm. They felt that the free-running rhythms in the three children were their own internal rhythms, revealed through some disorder in the brain mechanism supposed to synchronize to the normal 24-hour day. They postulated that the irregular sleep-wake rhythm in the fourth child may have been the result of immaturity or of failure of the pacemaker of the circadian (24-hour) rhythm. They also noted that, because of the severe degree of their mental retardation, all of the children were lacking in social time cues. Studies by Poindexter and Bihm (1994) would appear to confirm the importance of blindness on sleep patterns, since 15 of the 19 persons with blindness in their sample, 78.9%, exhibited chronic short sleep patterns, compared to 38.8% of their total sample.
Comings and Comings (1987) assessed a variety of markers, including presence or absence of sleep disturbances, in 247 consecutive persons with Tourette syndrome, 17 persons with attention-deficit disorder, 15 persons with attention-deficit disorder associated with Tourette syndrome, and 47 random controls. Sleep problems were pervasive in the individuals with Tourette syndrome, with a significantly increased frequency of sleepwalking, night terrors, trouble falling asleep, early awakening, and inability to take afternoon naps as a young child. They noted that in all diagnostic categories, including persons with mild Tourette syndrome, a total sleep-problem score was significantly higher than that of controls. They feel this is consistent with the theory that Tourette syndrome is a disorder of disinhibition of the limbic system of the brain.
Recent trends toward deinstitutionalization of persons with mental retardation have increased the importance of addressing factors that may interfere with community integration. Although a number of factors have been analyzed in an attempt to relate individual characteristics to success of community placements (Schalock & Lilley, 1986), very little attention has been paid to characteristics other than obvious behavioral or cognitive factors. One neglected area is that of patterns of sleep, even though atypical patterns would be expected to present far more problems in a small-group setting than they do in a large congregate facility. Certainly individuals with developmental disabilities would be expected to exhibit all of the types of sleep abnormalities seen in the general population.
Because of the apparent impact of atypical sleep patterns on the physical and mental health of persons with developmental disabilities, the area of assessment and management of these conditions appears to be a fruitful area for research for persons with mental retardation and behavioral/psychiatric conditions. While sleep laboratories and research centers are able to use complex electronic equipment to analyze sleep disorders, this usually is a time-consuming and expensive process. Most sleep disorders can be satisfactorily assessed with thorough, careful history and basic medical evaluation.
A good sleep history has a number of important aspects (Pary, Tobias, Webb, & Lippmann, 1996). Factors associated with the onset of the sleep problem, particularly medical or psychiatric conditions, should be discussed. Information about the usual sleep-wake schedule should include bedtime, awakening time, regularity of sleep schedule, and time usually required to go to sleep after the individual goes to bed. The sleep environment and bedtime routine should be explored, looking for factors which may lead to a state of over-arousal and nighttime disturbances. For persons with developmental disabilities, the latter may include an over-zealous nighttime toileting program (A. Eddy, personal communication, June 17, 1998). The number of nightly arousals/awakenings should be estimated, as well as any early morning symptoms of dry mouth or headache. Information about sleep behavior should also be obtained from any bed partner or other observer, such as family members or support staff personnel. Additional information should be obtained about daytime sleepiness, either during periods of inactivity or during times of day when alertness should be maximal.
Laboratory electrophysiologic testing and/or self-reporting are often not considered appropriate for the long-term study of individuals with marked degrees of mental retardation, who may exhibit severe behavior problems and often lack verbal skills necessary for self-reporting. The potential utility of behavioral study of sleep patterns was noted by Carroll and her group (1989), who demonstrated that behaviorally defined sleep/wakefulness could be reliably determined in a nursing home setting. They also noted that the diffuse slowing seen in the EEG in many institutionalized persons may interfere with defining sleep electrophysiologically. Interrater reliability for the study on institutionalized persons with profound mental retardation by Poindexter and Bihm (1994) was 0.91 for five subjects residing in one living area housing 16 persons. (Because of their large study group and long data set, they made no effort to check interrater reliability for each person studied.)
First step in assessment of a sleep disorder is careful definition of the chief sleep symptom, such as insomnia, excessive daytime sleepiness, or disturbed behavior during sleep (Kupfer & Reynolds, 1997). Studies (Leigh, Bird, Hindmarch, Constable, & Wright, 1988) indicate that the two most important aspects of subjectively perceived sleep are the process of going to sleep and the quality of sleep. Duration of symptoms is probably the most important guide to evaluation and treatment of insomnia (Gillin & Byerley, 1990). Appropriate treatment of temporary insomnia, with good sleep hygiene measures and possibly very brief drug treatment, may prevent development of longer-term sleep problems (Reite, Nagel, & Ruddy, 1990).
Most effective treatment programs for sleep disorders do not involve drug treatment, except for possibly very brief periods. Readers interested in more information about types of sleep disorders and appropriate treatments would do well to read carefully the short handbook developed by Reite and group (1990). Referral to specialized centers should probably be reserved for the most difficult, complex clinical pictures.
Brylewski, J. E. & Wiggs, L. (1998). A questionnaire survey of sleep and night-time behaviour in a community-based sample of adults with intellectual disability. Journal of Intellectual Disability Research, 42, 154-162.
Carroll, J. S., Bliwise, D. L., & Dement, W. C. (1989). A method for checking interobserver reliability in observational sleep studies. Sleep, 12, 363-367.
Clements, J., Wing, L., & Dunn, G. (1986). Sleep problems in handicapped children: A preliminary study. Journal of Child Psychology and Psychiatry, 27, 399-407.
Comings, D. E. & Comings, B. G. (1987). A controlled study of Tourette syndrome. VI. Early development, sleep problems, allergies, and handedness. American Journal of Human Genetics, 41, 822-838.
Dement, W. C. & Mitler, M. M. (1993). Its time to wake up to the importance of sleep disorders. Journal of the American Medical Association, 269, 1548-1550.
Gillin, J. C. & Byerley, W. F. (1990). The diagnosis and management of insomnia. New England Journal of Medicine, 322, 239-248.
Kupfer, D. J. & Reynolds, C. F. (1997). Management of insomnia. New England Journal of Medicine, 336, 341-346.
La Voie, A. (1997, April 17). Insomnia and related problems show alarmingly high rates. Medical Tribune, p. 6.
Leigh, T. J., Bird, H. A., Hindmarch, I., Constable, P. D. L., & Wright, V. (1988). Factor analysis of the St. Marys Hospital Sleep Questionnaire. Sleep, 11, 448-453.
Okawa, M., Nanami, T., Wada, S., Shimizu, T., Hishikawa, Y., Sasaki, H., Nagamine, H., & Takahashi, K. (1987). Four congenitally blind children with circadian sleep-wake rhythm disorder. Sleep, 10, 101-110.
Pary, R., Tobias, C. R., Webb, W. K., & Lippmann, S. B. (1996). Treatment of insomnia: Getting to the root of sleeping problems. Postgraduate Medicine, 100, 195-210.
Poindexter, A. R. & Bihm, E. M. (1994). Incidence of short-sleep patterns in institutionalized individuals with profound mental retardation. American Journal on Mental Retardation, 98, 776-780.
Reite, M. L., Nagel, K. E., & Ruddy, J. R. (1990). Concise guide to the evaluation and management of sleep disorders. Washington, DC: American Psychiatric Press.
Richdale, A., Gavidia-Payne, S., Francis, A., & Cotton, S. (1997, May). Sleep characteristics of children with an intellectual disability. Poster paper presented at the meeting of the American Association on Mental Retardation, New York, NY.
Salzarulo, P. & Chevalier, A. (1983). Sleep problems in children and their relationship with early disturbances of the waking-sleeping rhythms. Sleep, 6, 47-51.
Schalock, R. L. & Lilley, M. A. (1986). Placement from community-based mental retardation programs: How well do clients do after 8 to 10 years?. American Journal of Mental Deficiency, 90, 669-676.
Shibagaki, M., Kiyono, S., & Matsuno, Y. (1985). Nocturnal sleep of severely mentally retarded children and adolescents: Ontogeny of sleep patterns. American Journal of Mental Deficiency, 90, 212-216.
Shibagaki, M., Kiyono, S., & Takeuchi, T. (1985). Nocturnal sleep in mentally retarded infants with cerebral palsy. Electroencephalography and Clinical Neurophysiology, 61, 465-471.
Strollo, P. J. & Rogers, R. M. (1996). Obstructive sleep apnea. New England Journal of Medicine, 334, 99-104.
Wiggs, L. & Stores, G. (1996). Severe sleep disturbance and daytime challenging behaviour in children with severe learning disabilities. Journal of Intellectual Disability Research, 40, 518-528.
Young, T., Palta, M., Dempsey, J., Skatrud, J., Weber, S., & Badr, S. (1993). The occurrence of sleep-disordered breathing among middle-aged adults. New England Journal of Medicine, 328, 1230-1235.
For further information contact:
Ann R. Poindexter, M.D.
1024 Clifton Street
Conway, AR 72032