Historically, sleep problems were thought to have been rare in school aged children; however, recent studies do not support this. Figures vary, but overall prevalence of significant parentally-reported sleep problems have been noted in approximately 20 – 40% of children (e.g. Blunden, et al., 2004; Liu, Ma, et al., 2005; Liu, et al., 2000; Mindell, 1993; Mindell & Owens, 2003; Owens, 2008b; Paavonen, et al., 2000). This may be a conservative estimate due to under-reporting by parents (Blunden, et al., 2004; Gregory, Rijsdijk, & Eley, 2006).
The International Classification of Sleep Disorders (American Sleep Disorders Association, 1997) describes dyssomnias as being disorders that result in excessive daytime sleepiness or difficulty initiating or maintaining sleep. In children, common issues include bedtime resistance (15 – 25%), significant sleep onset delay and bedtime anxiety (10%), and parent- and teacher-reported daytime sleepiness (10%) (Mindell & Owens, 2003). Problems with sleep initiation or maintenance have been identified as a potential problem in as many as 30 – 40% of school-aged children (Fricke-Oerkermann, et al., 2007; Owens, Spirito, McGuinn, et al., 2000; Spruyt, et al., 2005). In general, studies suggest that children are not getting enough sleep, with an estimated 15 million children in America affected by inadequate sleep (Smaldone, Honig, & Byrne, 2007). The 2004 Sleep in America poll (National Sleep Foundation, 2004) also found that 27% of school-aged children were getting fewer hours sleep than their parents’ thought they should be having.
Parasomnias are defined in the International Classification of Sleep Disorders (American Academy of Sleep Medicine, 2005, p. 137) as “undesirable physical events or experiences that occur during entry into sleep, within sleep, or during arousals from sleep”. These include sleep walking, night terrors, sleep enuresis and sleep bruxism. Sleep walking and night terrors occur during NREM sleep, typically during the first two-thirds of the night (Capp, Pearl, & Lewin, 2005) and have been reported to occur
33 regularly in approximately 1 - 6% and 3 - 6% of children respectively (Agargun, et al., 2004; Mindell, 1993). Sleep bruxism, or teeth grinding, has been observed in approximately 6 - 35% of children and sleep enuresis, or bedwetting, in 1 – 10% of school-aged children (Liu, Ma, et al., 2005; Mindell, 1993; Ng, et al., 2005; Serra- Negra, Ramos-Jorge, Flores-Mendoza, Paiva, & Pordeus, 2009; Smedje, Broman, & Hetta, 1999; Wang, et al., 2007).
Obstructive sleep apnoea syndrome (OSAS) affects approximately 1 – 4% of children and is one of the most common respiratory disorders of childhood (Bixler, et al., 2009; Goldstein, et al., 2004; Kaditis, et al., 2004; Liu, Ma, et al., 2005; Robinson & Waters, 2008). It involves repeated episodes of upper airway obstruction during sleep (Mindell, 1993) and prevalence may be on the rise due to increasing rates of obesity and decreasing adenoid-tonsillectomy procedures (Capp, et al., 2005).
New Zealand prevalence data are sparse. Fergusson, Hons, Horwood, and Shannon (1986) reported 7.4% of 8-year-olds (N = 1,092) experienced nocturnal enuresis. Edwards, Hsiao, and Nixon (2005) reviewed paediatric home ventilator support in Auckland, indicating that over a 12-year period 160 children (89 boys) received home respiratory support for a number of conditions including (but not exclusively) OSAS. Notably, the availability and accessibility of services, as well as prevalence of conditions, may have influenced these figures.
1.6.1 Impact of Sleep Problems in Middle Childhood
Poor quality and insufficient quantity of sleep can result in children experiencing daytime sleepiness, decreased alertness and impairment of daily functioning (Figure 1.8). However, unlike in adults, sleepiness may present as disturbed mood, hyperactivity, poor impulse control and inattention. This may negatively impact social functioning, school performance and family relationships as well as increasing the risk of unintentional injury (Mindell & Owens, 2003).
Sleep problems have been associated with school attendance issues (OR = 2.53, 95% CI 1.45 – 4.41) and a greater number of teacher-reported psychiatric symptoms in 8 – 9-year-olds (N = 5,813) living in Finland (Paavonen, Almqvist, et al., 2002). Parents were more likely to report problems at school when children experienced inadequate sleep (Smaldone, et al., 2007), and a number of studies have found suboptimal sleep to affect school performance (Bruni, et al., 2006; Buckhalt, Wolfson,
INTRODUCTION
34 & El-Sheikh, 2009; Quach, Hiscock, Canterford, & Wake, 2009; Ravid, Afek, Suraiya, Shahar, & Pillar, 2009; Taras & Potts-Datema, 2005). Conversely, better sleep was identified as a protective factor for children, moderating the effects of emotional insecurity and parental attachment difficulties and resulting in improved academic performance (El-Sheikh, Buckhalt, Keller, Cummings, & Acebo, 2007; Keller, Ei- Sheikh, & Buckhalt, 2008).
Figure 1.8. Relationship between sleep disturbance, daily functioning and injury. Adapted from Owens, J. A., Fernando, S. & McGuinn, M. (2005). Sleep Disturbance and Injury Risk in Young Children. Behavioral Sleep Medicine 3(1), 18 – 31.
Childhood sleep difficulties have been associated with anxiety and depression (Chorney, Detweiler, Morris, & Kuhn, 2008; Gregory & Eley, 2005; Gregory, Rijsdijk, Dahl, McGuffin, & Eley, 2006), with anxiety having a stronger association with sleep problems in children aged 6 – 11-years and depressive symptoms with teenagers aged 12 – 17-years (Alfano, et al., 2009). Overall, Paavonen and colleagues (2003) found
35 current sleep difficulties in preadolescent children to be associated with an increased risk of psychiatric problems (OR = 2.92, 95% CI 1.58 – 5.38).
Behaviour has also been linked to sleep problems (Paavonen, Porkka-Heiskanen, & Lahikainen, 2009), particularly hyperactivity and inattention (Melendres, Lutz, Rubin, & Marcus, 2004; Urschitz, et al., 2004). Associations were found between hyperactivity and bedtime resistance, restless sleep, and sleep walking. Bedtime resistance was also associated with conduct problems (Bos, et al., 2009; Smedje, Broman, & Hetta, 2001). Actigraphically measured short sleep duration (< 7.7 hours) was a significant predictor of hyperactivity and impulsivity in 7 – 8-year-olds (N = 280) (Paavonen, Raikkonen, et al., 2009). Additionally, sleep problems at the age of 4-years were found to predict emotional and behavioural problems in mid-adolescence, highlighting the importance of the detection of sleep issues early in life (Gregory & O'Connor, 2002).
In an analysis of children attending an emergency centre in Italy due to injury, Valent, Brusaferro, and Barbone (2001) found a direct association between injury and sleeping < 10 hours for boys (RR: 2.33, 95% CI 1.07 – 5.09) but not girls (RR: 1.00, 95% CI 0.29 – 3.45). A significant association was also found between injuries occurring between 16:00 and midnight (girls and boys, RR: 4.00, 95% CI 1.13 – 14.17). Additionally, a circadian pattern in childhood traumas with an afternoon peak at 16:00 was found by Reinberg, Reinberg, Téhard, and Mechkouri (2002). In a study of 6 – 13- year-olds (N = 389), CSHQ subscale scores for parasomnias and daytime sleepiness were positively associated with injury, as was shorter sleep duration (< 9 hours) (Li, et al., 2008). Owens, Fernando and McGuinn (2005) also found that 3 – 7-year-olds who were reported to be more injury-prone by their parents had significantly more sleep disturbance than their counterparts.
Overall, sleep problems have been associated with poorer quality of life of children (Crabtree, Varni, & Gozal, 2004; Hart, Palermo, & Rosen, 2005). It is not surprising that negative effects are experienced not just by individuals, but also by other family members. Poorer parental health, and in particular maternal mental health, has been associated with children’s sleep issues, (Fauroux, Aubertin, & Clement, 2008; Martin, Hiscock, Hardy, Davey, & Wake, 2007; Meltzer & Mindell, 2007). Maladaptive behaviours have been found to occur in parents of children with sleep problems (Simard, Nielsen, Tremblay, Boivin, & Montplaisir, 2008) which may also impact siblings. Given the difficulties outlined regarding mood, behaviour and school
INTRODUCTION
36 problems, children’s sleep issues may impact community services and members such as teachers and health professionals.