Introduction
Autism Spectrum Disorder (ASD) is a complex developmental disorder that has an estimated prevalence of 1 in 54 children in the United States (U.S.) [
1]. It presents challenges in many areas of early child development, such as communication, socialization, learning, and adaptive behavior. [
2] These challenges can potentially impact the primary caregiver and family, as well as the child with ASD. The additional difficulties presented in advocating for services and opportunities, and the long-term expense needed for care of their children create higher levels of stress for caregivers of children with ASD [
3,
4,
5,
6]. Additionally, caregiving demands of a child with ASD can interfere with attending to needs of other family members and interfere with self-care. [
7]
Sleep disturbances in children with ASD are reported by their parents at a prevalence of 58% to 80% [
8,
9]. Parents of children with ASD tend to be hypervigilant at night due to the possibility of unsafe activity by their children with ASD that may result in nighttime behaviors such as self-injury, property damage, or escape from their homes [
10]. Additionally, the added stress related to the overall care of children with ASD may promote the development of insomnia. Although several studies have explored the health related quality of life (HRQoL) of parents/caregivers relative to the challenges presented by children with ASD [
11,
12,
13], there are scant data pertaining to the impact of poor sleep on HRQoL in these parents/caregivers.
Family quality of life (FQoL) is a distinct and multidimensional construct in the field of disability and acknowledges the importance of the family as the primary support and decision-makers for young children with disabilities [
14]. It includes multiple domains of family wellbeing and addresses the intersection of the needs of the individual with a disability and the needs of other family members [
15]. Families with children who have ASD report a more profound impact on their quality of life than families of children with other disabilities (i.e., Attention Deficit Disorder, Attention Deficit Hyperactivity Disorder) or families of typically developing children [
16].
This study investigated the prevalence of sleep disorder symptoms in caregivers of children with ASD. Additionally, it explored the relationships between caregiver sleep problems and their HRQoL and FQoL.
Statistical Analysis
All data were analyzed using SPSS version 22 (SPSS Inc., Chicago, IL). Descriptive statistics were computed for all variables. Means and standard deviations (S.D.) were calculated for continuous variables, and percentages were reported for categorical variables. Student’s T-test measured associations between sleep disorder symptom variables and the dependent variables HRQoL and FQoL. Correlations were used to determine associations between health conditions and sleep duration, HRQoL, and FQoL. Partial correlations evaluated the relationship between sleep duration and quality of life (i.e., MCS, PCS, FQoL) controlling for caregiver age, family income, and the number of caregiver health conditions.
Dichotomized variables were created from the non-restorative sleep, insufficient sleep, and insomnia responses collected from the SHQ. These variables were coded as “0” for participants who endorsed having symptoms “never,” “rarely (1 day a month),” or “sometimes (2-4 days a month)” and as “1” if the participant endorsed having symptoms “often (1-3 days a week)” or “almost always (4 or more days a week)”. A score > 10 on the ESS was coded as “1” or “yes” for excessive daytime sleepiness. A score of < 10 was coded as “0” or “no.”
Caregivers reported their average sleep duration during the weekday and on the weekends. Average sleep duration was calculated as
The Physical (PCS) and Mental Composite Scales (MCS) derived from the SF-12 were used to describe HRQoL. The calculation of the PCS and MCS used the algorithm provided by Ware et al., [
24] and higher scores indicate a higher perceived HRQoL. Pearson correlations analyzed the strength in the relationships among caregiver age, caregiver sleep duration, HRQoL, and FQoL. The level of statistical significance was established at p≤0.05.
Results
Table 1 provides a summary of the socio-demographic characteristics of the study participants. The caregivers who participated in the survey were, on average, 40.23 years old (
SD = 4.4), mothers (92%), married (93.5%) and Non-Hispanic White (79%). More than half (53.2%) reported their household income to be more than
$100,000 and all attended at least “some college.” Fifty-eight percent of the caregivers were employed either full-time or part-time. The respondents had an average of 2.23 dependent children (
S.D. = .92) living with them. The mean age of the children with ASD was 7.61 (SD 1.54) years, and 80.6% were boys.
The prevalence of caregiver health conditions is shown in
Table 2. Depression (25.8%), asthma (17.7%), and overweight/obesity (19.4%) were the most common provider diagnosed health conditions. Caregivers experienced a mean of 1.16 (
SD = 1.23) health conditions with a range between 0 and 5.
Table 2 also presents the prevalence of various self-reported sleep symptoms and sleep duration. The average sleep duration was 6.4 hours (
SD = 0.97) per night but was 6.2 (
SD = 1.0) hours of sleep on the weekdays and 6.7 (
SD = 1.13) hours of sleep on weekends. Eighty-two percent of participants had a short sleep duration, defined as
< 7 hours per night. Some caregivers reported as little as 4 hours of sleep per night; no caregivers reported sleep durations of > 8 hours per night. Insufficient sleep was reported in 54.8% of the cohort. At least one insomnia symptom was present in 54.8% of the participants with difficulty falling asleep, difficulty getting back to sleep if they wake up during the night, and the inability to return to sleep if they wake up too early in the morning noted in 32.2%, 23.2% and 27.4% respectively. On average, caregivers reported that their average sleep latency was 23 minutes (
SD = 19, range: 0-90 minutes). Sleep onset problems, defined as taking
> 30 minutes to fall asleep at bedtime, were reported by 40.3%. Fifty percent reported non-restorative sleep and 26% reported excessive daytime sleepiness (ESS >10).
The prevalence of self-reported sleep conditions is displayed in
Table 2. Restless legs syndrome was endorsed by 24.2% of the cohort. However, only one participant (1.6%) had health provider diagnosed RLS. Frequent snoring (two nights a week or more) was reported by 19.3% of the participants. Symptoms of obstructive sleep apnea were reported by 9.7% of the caregivers in this study, and two caregivers (3.2%) had been diagnosed with sleep apnea by a health care provider.
Means, standard deviations, and the range of scores are reported in
Table 3 for the Physical Composite Scores (PCS) and the Mental Composite Scores (MCS) on the SF-12. The Cronbach’s alpha for the SF-12 in this study was .74, indicating acceptable internal consistency. Overall, the PCS mean score was 51.85 (
SD = 7.58), and the MCS score was 44.95 (
SD = 9.34). When compared to the U.S. general population of adults ages 35-45, [
24] there were no significant differences between the physical health (PCS) of the caregivers in the present study and the physical health (PCS) of the U.S. general population (
M = 52.18,
SD = 7.70),
t(61) = -.34,
p = .74. However, mental health scores (MCS) are significantly lower (poorer) in the present study than the scores of the U.S. general population [
24] (
M= 44.95,
SD=9.34)
t(61) = -4.34,
p < .001. Caregivers who reported arthritis or asthma were more likely to report lower HRQoL in their physical health, whereas caregivers who reported heart disease were more likely to report lower HRQoL in mental health. Participants with arthritis or cancer were more likely to report a poorer FQoL. There were no significant relationships between health conditions and sleep duration or insomnia symptoms.
The means, standard deviations, and range of scores for the Beach Center FQoL scale total score and five subscales are shown in
Table 3, with higher scores indicating a better FQoL [
25]. The Cronbach’s alpha for the five subscales of the FQoL for this study was .80, which indicates good internal consistency. The means of the five domains rated from highest to lowest were 1) Physical and Material Wellbeing, 2) Parenting, 3) Family Interaction, 4) Disability Support, and 5) Emotional Wellbeing. The sequence of highest to lowest domains and the total score (M=3.92, S.D.=.61) is similar to prior studies using the Beach Center FQoL Scale with U.S. families who have children with ASD [
26] (
M= 3.5,
SD=.76)
t(105) = 4.46,
p < .001.
Table 4 displays the associations between sleep disorder symptoms and self-reported insomnia, obstructive sleep apnea, and restless legs syndrome. Scores on the PCS of the SF12 were significantly lower in participants who had difficulty falling asleep (
M=48.71, SD=8.55 vs.
M=53.35, SD=6.58, p=0.02), sleep onset ≥ 30 minutes (
M=49.37, SD =8.31 vs.
M=53.53, SD=6.65, p=0.03), obstructive sleep apnea (
M=45.89, SD=10.00 vs.
52.49, SD 7.10, p=0.042) and restless legs syndrome. (
M=50.85, SD=8.31 vs.
M=54.99, SD=3.11, p=0.006). Scores on the MCS were lower for combined insomnia symptoms (
M=42.50, SD=8.18 vs.
M=47.91, SD=9.92. p=0.02), difficulty falling asleep (
M=41.37, SD=8.64 vs.
M=46.65, SD=9.27, p=0.04), early morning awakenings
(M=40.28, SD=7.05 vs.
M=46.71, SD=9.55, p=.01), non-restorative sleep (
M=40.64, SD=9.9 vs.
M=49.26, SD=6.28, p≤
0.001), and insufficient sleep (
42.08, SD=8.65 vs.
M=48.72, SD=9.13, p≤
0.005). The presence of non-restorative sleep (
94.79, SD 14.04 vs.
M=103.3, SD=16.12, p=0.02) and insufficient sleep (
95.16, SD=14.01 vs.
M=104.13, SD=14.49, p=0.02) were associated with lower scores on the FQoL. A lower score on the FQoL for sleep durations <6 hours approached statistical significance (
M=93.58, SD=10.72 vs.
M=101.28, SD=15.60, p=0.06).
Table 5 shows the bivariate correlations between the SF-12 and FQoL, and sleep duration and number of co-morbid health conditions. There was a negative correlation between the number of caregiver health conditions and the SF-12 PCS demonstrating that caregivers who reported more health conditions reported poorer physical health (r=0.40, p<0.05). Caregiver sleep duration was correlated with the SF-12 MCS (
r = .28, p<0.05) and FQoL (r=.37, p<0.05). Therefore, caregivers with longer sleep duration reported better mental health and better FQoL. Partial correlation analyses demonstrated that the relationship between sleep duration and mental health remained when controlling for caregiver age, income, and number of health conditions. (r
partial=0.30, p=0.022). Similarly, controlling caregiver age, income and number of health conditions did not attenuate the association between sleep duration and the FQoL (r
partial=0.37, p=0.004). There also was a positive correlation between the SF-12 MCS and the FQoL after controlling for sleep duration, age and health conditions (r
partial=0.44, p<0.001) indicating that caregivers who reported better mental health also reported better family quality of life.
Discussion
This exploratory study found high prevalence rates of self-reported sleep disorders and symptoms of sleep disorders among caregivers of children aged 6-11 years diagnosed with ASD. Furthermore, sleep disorders and their symptoms were associated with adverse impacts on physical and mental components of HRQoL of these caregivers as well as FQoL of their families. These results support the hypothesis that caregiver sleep problems lead to worse health-related individual and family quality of life.
The average sleep duration for caregivers in this study was 6.4 hours, less than the recommended minimum of 7 hours for adults [
27]. Consistent with the low average sleep duration was our finding that 54.8% of the cohort reported that they obtained insufficient sleep. Short sleep duration in large general population studies is related to increased risk of cardiovascular disease, hypertension, diabetes, depression, early mortality, and a number of other health problems [
28]. Our finding that insufficient sleep was associated with worse scores on the MCS of the SF-12 agree with these previous results and suggest that caregivers of children with autism may be at particular risk for mental health issues. In contrast, insufficient sleep was not associated with lower scores on the PCS of the SF-12. Previous studies have observed a reduction in the PCS of the SF-36 in association with shorter sleep durations [
29,
30]. These latter studies focused on elderly cohorts; therefore, it is possible that the younger ages of our participants mitigated any adverse impact of short sleep duration on their physical health. Future studies that include information on health habits (i.e., diet, exercise) and relevant socioeconomic (SES) factors (e.g., access to medical care, income, education) are necessary to understand any associations. Longitudinal studies are also needed to investigate the long-term effects of short sleep duration on the physical and mental health of caregivers of children with ASD.
Insomnia symptoms were the most frequently reported sleep problem by the caregivers of children with ASD. The prevalence of any symptom of insomnia was 54.8% which is higher than the 27.3% reported in adults in the U.S [
31]. Possible explanations for this higher rate of insomnia include greater stress and anxiety among caregivers as well as increased rates of depression and restless legs syndrome. There is a bidirectional relationship between insomnia and depression; insomnia is a risk factor for depression [
32] and conversely one manifestation of depression is insomnia [
33]. Importantly, 26% of the caregivers in the present study reported a diagnosis of depression, providing support for the role of depression as an etiology for insomnia in our cohort. Additionally, the prevalence of RLS in the cohort was 24.2% which is higher than the 14.5% rate reported in a multinational systematic review of 34 studies [
34]. It is likely that RLS also is contributing to the high prevalence of insomnia in our cohort inasmuch as one of the primary consequences of RLS is insomnia [
35].
Insomnia among the caregivers in this study was strongly associated with reductions in the MCS of the SF-12. Previous studies documented that insomnia is related to poor mental health in several chronic health conditions as well as in the general population [
36]. It is likely that the high prevalence of depression in our cohort is contributing to the adverse impact of insomnia on the MCS. Previously, we documented that RLS in caregivers of children with ASD is associated an increase in insomnia symptoms and a corresponding reduction in quality of life [
37]. Insomnia and RLS are treatable conditions; addressing both in caregivers provides an opportunity to improve their mental health and overall HRQoL.
Although two important symptoms of OSA, snoring and excessive daytime sleepiness, did not show associations with HRQoL, our definition of OSA was related to a reduction in the PCS of the SF-12. Previous studies in the general population have demonstrated that OSA adversely impacts the PCS component of the SF-36 [
38,
39]. Studies of quality of life using other instruments have shown negative effects from OSA [
40]. In some reports, however, only severe OSA manifested a significant reduction in the PCS. Although the severity and treatment status of participants with OSA are unknown, our results are consistent with these previous studies showing an adverse impact of OSA on HRQoL. It would be important, therefore, for caregivers of a child with ASD to seek evaluation and treatment for OSA if there are any suggestive symptoms; treatment for OSA has been shown to improve quality of life [
41].
Caregivers who had shorter sleep durations were more likely to report poorer FQoL. Poorer FQoL was also reported by caregivers who endorsed non-restorative sleep and insufficient sleep. These relationships are noteworthy; however, the underlying explanation is unknown. In previous research, positive social relationships have been associated with more satisfactory FQoL [
42]. Both sleep and social support have broad influences on physical and mental health and there is an association between greater social support and more favorable sleep outcomes [
43]. Family functioning can have a significant influence on the sleep habits of the primary caregiver, the child with ASD, as well as other family members. Although the families in this study generally had higher incomes, families who have fewer economic resources may live in tighter living quarters that create challenges in maintaining sleep environments that are quiet, dark, and have a comfortable temperature—conditions conducive to good quality sleep. [
44] Bedtime practices that promote sleep, such as consistent bedtime routines, are less likely to occur in a family who lives in poverty or overcrowded housing conditions [
45,
46]. Short sleep duration and sleep problems that include trouble falling and staying asleep have been associated with lower SES [
47]. Future research that includes information from multiple family informants about the sleep environment and family sleep habits as well as multiple perspectives of FQoL would be valuable.
There are limitations to this research. The study consisted of a small convenience sample of caregivers of children with ASD, and these results may not necessarily be generalizable to other caregivers of children with ASD. Additionally, because of the descriptive cross-sectional nature of this study, causality should not be inferred. This study also relied on the self-report by caregivers of their sleep disturbances. Thus, misclassification could have occurred. The consistency of our findings demonstrating the adverse impact of sleep problems on HRQoL and FQoL, however, strengthen their validity.
Despite these limitations, there are several major strengths of this study, including a confirmed diagnosis of the children with ASD through an ADOS or ADOS2 that have strong sensitivity and specificity for diagnoses. [
18]
, [
19] Importantly, this study addressed the impact of caregiver sleep on both HRQoL and family functioning. There has been increasing attention paid to interventions and policies enhancing the value of the family as long-term foundational support for individuals with ASD and their caregivers. This study supports such initiatives and sheds light on the importance of caregiver sleep and health and their subsequent effect on FQoL.