Sleep is an integral part of any person’s life; it is especially more crucial for children. Studies show that children, up to two years old, have spent approximately 40% of their life asleep (Simpkin et al., 2015). Sleep is of particular importance to children since it aids in physical and mental growth. There are two general states of sleep; Non-Rapid Eye Movement (NREM) that is characterized by a deep sleep, it is in this state that children go through the physical and mental growth. The second state is the Rapid Eye Movement (REM), in this state, the brain is active and dreaming occurs. Toddlers need approximately 12-14 hours of sleep each day; their sleeping patterns are determined by their circadian clock and chronotype.
The circadian clock is the body’s way of coordinating its activities and behaviors in vis-à- vis the environmental changes around it, specifically the day-night cycle. The circadian clock is controlled by the suprachiasmatic nuclei (SCN) of the anterior hypothalamus (LeBourgeois et al., 2013). Studies show that the circadian phase is responsible for sleeping patterns; this is the sleep time, wake time, and sleep duration. The circadian clock develops over time; this explains why infants have irregular sleeping patterns; however, it stabilizes after about 3-6 months. To investigate the circadian phase researchers’ measure levels of melatonin as it has been proven that melatonin levels rise before sleep (Akacem et al., 2015).
Le Bourgeois et al. (2013) investigated the impact of the circadian phase on nighttime sleep pattern in toddlers. Their research showed that healthy toddlers had a rise in melatonin levels at 1929h on average, the times ranged from 1735h to 2107h. As stated, the circadian cycle determines the body’s behavior during the day-night cycle. The ‘lights-off’ time selected by parents for their toddlers has an enormous influence on their circadian phase for bedtime and wake time (LeBourgeois et al., 2013). Research by Akacem et al. (2015) sheds more light on bedtime and circadian phase in toddlers. Their study showed that toddlers that took naps had a later onset of melatonin; they had later bedtimes. The wake times were similar to non-nappers, both nappers and non-nappers spent the same amount of time sleeping in a 24-hour period. Their study also showed that toddlers who napped took longer to fall asleep and they slept fewer hours during the night.
The second factor affecting sleep in toddlers is chronotype; it depicts a person’s circadian rhythms. Chronotype determines whether a person prefers morningness or eveningness. Simpkin et al. (2015) conducted studies that analyzed the link between chronotype and circadian clock on a sample of 48 healthy toddlers. Their research found that chronotype is not constant; however, most toddler exhibit a tendency towards morningness, they are most active in the morning. The onset of melatonin was shown to influence chronotype in that kids with later circadian phases tended towards eveningness (“owls”).
An understanding of chronotype can help in alleviating many parents’ concern on what is the best time to put their children to sleep. A child’s bedtime is influenced extrinsically [by parents] and intrinsically [child determined]; however, the largest influence comes from the parents. Parents can determine the best time to put a child to bed by knowing their chronotype. Studies show that putting a child to bed to close to their dim light melatonin onset (DLMO) time is a leading cause of sleep resistance (Simpkin et al., 2015). Early childhood is a crucial phase in development and sleep plays a big role making it imperative for both parents and scholars to learn all the aspects of sleep in this period.
