Sleep is a critically important yet understudied phenomenon in psychology and education. Parents and others often talk about preschoolers' sleep. They express concerns ranging from how much sleep is appropriate to difficulties with night awakenings. Many a visit with the pediatrician involves a discussion about sleep patterns. However, suggestions offered by clinicians, grandparents, and family friends are often based on personal experience or generally accepted yet unexamined and unsupported guidelines (US Department of Health and Human Services; HHS, 2003). Despite the attention given to sleep disorders in the medical and medically-related literature, little is known about normal human sleep (HHS, 2003) including typically-developing preschool children's sleep patterns (Bates, Viken, Alexander, Beyers, & Stockton, 2002).
Sleep accounts for 40% of the daily life of children and adolescents (Mindell & Owens, 2003) and is central to the preschool child's development and growth (HHS, 2003). More specifically, sleep is associated with preschoolers' behavior and cognitive readiness for learning (Bates et al., 2002). A more regular sleep schedule is also associated with preschool adjustment. Children with a regular sleep schedule adjust better to preschool than their peers with more disrupted sleep patterns (Bates et al., 2002). Regular and earlier bedtimes are also associated with fewer behavioral difficulties (Hale, Berger, LeBourgeois, & Brooks-Gunn, 2010). Conversely, less sleep at night and during a 24 hour period has been linked with a higher number of externalizing behavior problems such as defiance (Lavigne et al., 1999). Consistent with this line of inquiry, a regular bedtime was found to be the greatest predictor of a developmentally appropriate outcome at age 4, with less hyperactivity, inattention, and impulsivity manifested (Gaylor, 2010). For all of these reasons, sleep is an important area for psychologists to consider.
Although the National Sleep Foundation (NSF, 2011) recommends preschoolers get between 11-13 hours of sleep per night, there is no evidence to show this has been or continues to be normative or optimal in any setting. Overall, despite its limitations, sleep research shows wide variation in preschoolers' normative sleep patterns, some of which are associated with demographic differences (Hale et al., 2009; HHS, 2003).
Preschool children's sleep patterns are important to study given their association with daily behaviors, adjustment, and learning (Bates et al. 2002; Hale et al., 2009; Lavigne et al., 1999). In addition to filling a much needed gap, the study of sleep patterns has the potential to contribute to the school readiness, early identification of developmental concerns, and an intervention knowledge-base. Furthermore, the identification of current sleep patterns for a typically- developing sample would provide additional evidence about current sleep guidelines (NSF, 2011) and foundational biological aspects of normative functioning. Third, given the long, intermittent interest in sleep research (Matricciani, Olds, & Petkov, 2011), we posited that looking at current data within a historical context would provide information about preschool children's sleep patterns over time. The next section offers a review of published research focused on preschoolers' sleep over the last century.
The Historical Context of Sleep
The first known large-scale observational studies of preschooler sleep were published primarily by women in the 1920s (Chant & Blatz, 1928; Flemming, 1925; Foster, Goodenough, & Anderson, 1928). For example, Flemming discovered the recommended but unnamed schedules for sleep provided by pediatricians and child-care specialists to be vastly different than her findings. Experts recommended sleep allotments for 3-4 year olds of 12-14 hours per night as reported by Foster et al. (1928). …