Like many children, my 6-year-old daughter is often very resistant to having an enforced bedtime. What can you do as a parent to synchronize your child's internal clock so that he or she can fall asleep more easily? New research offers some simple ways to reduce sleep resistance and insomnia for toddlers, and people of all ages.
For most children, sleep disturbance can include: difficulties falling asleep, bedtime resistance, tantrums, and episodes known as "curtain calls" which manifest themselves as a calling out from bed or coming out of the bedroom—asking for another story, glass of water, something to eat, a bathroom trip...
A December 2013 study titled “Circadian Phase and Its Relationship to Nighttime Sleep in Toddlers” from CU-Boulder has found that sleep problems in early childhood have been linked to later emotional and behavioral problems, as well as impaired cognitive function. Parents of young children with sleep problems often report increased difficulties in their own sleep patterns, which creates a vicious cycle of familial fatigue and potential emotional discord.
The Boulder study showed that toddlers who are exposed to bright artificial bright light after sunset can develop a later rise time for melatonin. Later melatonin rise times make it more difficult for a child to wind down and fall asleep after being put to bed, according to CU-Boulder Assistant Professor Monique LeBourgeois.
According to the researchers, the bedtime you select for your toddler may be out of sync with his or her internal chronobiological clock, which can contribute to difficulties for youngsters attempting to settle down for a good night’s sleep. The study pinpointed the time when the hormone melatonin increased in the evening, indicating the start of the biological night, in a group of 14 toddlers whose sleep also was studied over the course of six days. The findings are important because about 25 percent of toddlers and preschoolers have problems settling after bedtime.
Chronobiology vs. Light Bulbs
Thomas Edison made the first public demonstration of the electric light bulb on December 31, 1879. At the time he declared, "We will make electricity so cheap that only the rich will burn candles." In 1882, Edison opened his Pearl Street Power Station which for the first time provided electricity to 59 customers in lower Manhattan. Electrical lighting did not became widely available in the United States until the 1930s.
Like every organism, our bodies have evolved for millennia to be in synchronized with the rising and setting of the sun. It’s amazing to think that our internal biological clocks have had less than 100 years to adapt to artificial light in the hours before bedtime and throughout the day in offices and classrooms with no natural light. It’s not surprising that in a modern age, many of us are short-circuiting due to our circadian rhythms and chronobiological clock being out of sync with the phases of the sun.
Before the 20th century, our sleeping, waking, and working patterns were based solely on available daylight and seasonal changes in the rise and set time of the sun. Sleep disorders have become an epidemic for people of all ages in the United States. In many cases, chronic insomnia is caused by one’s internal clock being thrown out of whack by increased exposure to artificial light and screen time througout the day and in the hours before bed.
The researchers have a hunch that it’s especially important to expose oneself to natural light first thing in the morning—and throughout the day if possible—to keep your internal clocked synchronized with the circadian phase. The “master clock” that controls circadian rhythms consists of a group of nerve cells in the brain called the suprachiasmatic nucleus, or SCN. The SCN contains about 20,000 nerve cells and is located in the hypothalamus. Destruction of the SCN results in the complete absence of a regular sleep–wake cycle.
Dimming Lights After Sunset May Help Keep Melatonin in Sync
"There is relatively little research on how the chronobiology of toddlers may contribute to the emergence of sleep problems," said LeBourgeois. "Sleeping at the wrong 'biological clock' time leads to sleep difficulties, like insomnia, in adults." Unfortunately, the schedules of modern life do not change with the seasons. Adults can choose their own bedtime to a wide degree, but toddlers rarely have this option and require much more sleep than adults, which creates a double-whammy.
A 2012 study led by LeBourgeois indicated toddlers show more anxiety, less joy and interest, and have a poorer understanding of how to solve problems when they missed their regular afternoon nap versus when they napped. These results suggested that children who miss out on needed sleep don't benefit from positive life experiences and have problems coping with day-to-day challenges.
The new study showed several toddlers who were put to bed before their natural rise in melatonin took 40-60 minutes to fall asleep. "For these toddlers, laying in bed awake for such a long time can lead to the association of bed with arousal, not sleep," LeBourgeois said. "This type of response may increase children's lifelong risk for insomnia over time."
The average evening melatonin onset for the toddlers occurred at roughly 7:40 p.m., which was about 30 minutes before parent-selected bedtimes, said LeBourgeois. On average, the toddlers fell asleep about 30 minutes after being tucked in for bed. "It's not practical to assess melatonin levels in every child," LeBourgeois said. "But if your child is resisting bedtime or having problems falling asleep, it is likely he or she is not physiologically ready for sleep at that time."
Circadian phase and its relation to sleep are increasingly recognized as fundamental factors influencing human physiology and behavior. Dim light melatonin onset (DLMO) is a reliable marker of the timing of the circadian clock, which has been used in experimental, clinical, and descriptive studies in the past few decades.
Although DLMO and its relationship to sleep have been well documented in school-aged children, adolescents, and adults, very little is known about these processes in early childhood prior to this new research. "This study is the first to show that a poor fit between bedtimes selected by the parents of toddlers and the rise in their evening melatonin production increases their likelihood of nighttime settling difficulties," said LeBourgeois.
Conclusion: Create an Optimal Evening and Sunrise Light Environment
"A natural next step is to optimize our knowledge of the interactions between physiology and the environment to further understand how problems like bedtime resistance first develop and how they are maintained," LeBourgeois concluded. Adding, "We believe that arming parents with knowledge about the biological clock can help them make optimal choices about their child's activities before bedtime, at bedtime, and his or her sleeping environment.”
Research in adolescents and adults has also shown that exposure to bright light and excessive screen time in the evening can delay the timing onset of melatonin. Whether the rise of melatonin in some toddlers can be pushed to an earlier time by restricting evening light or by increasing morning light exposure is a question that requires more research, but it appears that this combination helps synchronize most internal clocks.
If you’d like to read more on this topic, check out my Psychology Today blog posts: