Dear Dr. Debbie,
I’ve been following the progress — and inaction — toward shifting Anne Arundel County’s high school start times that is supposed to reflect research on adolescent sleep. I’ve heard both sides mention the “science” behind this, but it doesn’t seem enough to make this a budget and staff priority for AACPS. What does the science actually say?
Looking Ahead for My Babies
Don’t miss last week’s column Exploring Trauma Informed Care — Good Parenting
The science behind teens’ sleep needs goes all the way back to technology in use in 1953 when sleep science had its beginnings. This was the discovery of REM sleep. Rapid Eye Movement is the phase of sleep during which dreaming occurs — marked with rapid eye movements under closed lids. Today, colleges offer degrees in Neurodiagnostics and Sleep Science with state of the art equipment to record and study the electrical activity of the brain, spinal cord and peripheral nerves as well as sleep effects on other important systems of the human body. Sleep and learning is a field gaining ground in recent years with implications for the best timing of high school and students’ sleep. (A short history of sleep science was recapped in 2005 by the Journal of Clinical Sleep Medicine published by the US National Library of Medicine at the National Institute of Health.) Continuing discoveries and confirmations have connected a good night’s sleep with many brain and body functions, some of which are critical for teens.
Here on planet earth, humans are powered by solar energy. Sunlight stimulates our brains on a 24-hour cycle effecting many biological processes including alertness, appetite and digestion, body temperature, and mood. On dark dreary days, and in the early morning hours before the sun is up, it’s harder to get out of bed.
Over a typical 24-hour period, there is a rise and drop in the brain’s secretion of melatonin — the hormone that makes you drowsy. The work of melatonin peaks at about the 4 to 4 ½ hour mark of an 8 to 9 hour nightly dose of sleep.
A report by the National Sleep Foundation in 2000 summarized Adolescent Sleep Needs and Patterns as a research report and resource guide. This information has helped bring awareness, and in some school districts, action, for improving the lives of our high schoolers. The work of sleep physiologist Mary Carskadon, who holds a doctorate in neuro- and biobehavioral sciences, reported that teens not only need more sleep than they did when they were younger (about 9 ¼ hours) with the cascade of body changes brought on by the hormones of puberty, they also undergo a phase shift. That is, melatonin rises and falls about 3 hours later than it did when they were younger. This means that an adolescent’s brain starts shutting down around 11 p.m. as compared to the 8 p.m. shutdown time of a school aged child. The result is still too much melatonin in the brain to let most teens rise and shine for a day of school that has them in first period class at 7:17 a.m. At sleep labs at Brown University’s Bradley Hospital, Carskadon found that not only were her 3,000 teenage subjects too full of melatonin when they had to rise too early in the morning, but for many of them there were elevated levels of the drowsiness inducing hormone all day long.
Learning is primarily a process of remembering. The student takes in information from the text book, the website, the lecture, or the demonstration and holds it in short-term memory until bedtime. Other conscious experiences are also temporarily stored (in a seahorse shaped organ of the brain called the hippocampus) until sleep. This includes “aha” moments of putting different information together for the student who has just gained a new understanding about what started the Civil War, as well as a discovery after one too many bad experiences about choosing the right friends. During REM sleep new information gets reviewed and put into long term storage in complex nerve pathways. The ability to retrieve a memory and put good information to use is important for academic success as well as successful relationships. That Civil War insight can then later be applied in a history essay and the relationship insight will be put to good use at the lunch table.
When dreamers of all ages are studied with an electroencephalogram (EEG), the graph showing brain wave activity reveals an increase in spikes during REM sleep. These have been named “sleep spindles.” More and larger sleep spindles correlate with better ability to recall information and perform tasks that were learned before a nap or before a good night’s sleep. Carskadon and other sleep scientists observe that longer REM sleep – the kind of sleep that boosts memory and judgement – happens in the morning hours. This learning time shouldn’t be interrupted by an alarm clock. It is not only the amount of sleep that helps students do well in school, but how much of their sleep time is spent with good sleep spindle activity going on.
Down time is also part of a good night’s sleep for the brain. Research on such things as reaction time, coordination and clear thinking demonstrate what a difference we can expect in our performance when there has been sufficient rest. Learning, it turns out, happens more easily with a fresh brain. Proteins build up during a day of thinking, which is experienced as mental fatigue.
One of the processes during our slumbers is that the connecting spaces between neurons – the synapses – are literally cleared out to a greater or lesser degree. Dr. Chiara Cirelli. at the Center for Sleep and Consciousness at the University of Wisconsin’s School of Medicine, Department of Psychiatry says, “Much of what we learn in a day, we don’t really need to remember.” The discarded connections are deemed less important or even incongruous with knowledge, skills and beliefs that are more firmly in place. Likewise subject matter with emotional connections will outrank more mundane experiences (and boring lessons) which could be lost overnight. During sleep the fluid surrounding brain cells clears away the protein buildup making room in the synapses for tomorrow’s lessons. Tangled neurons release their hold on each other, readying for new connections tomorrow. “If you’ve used up all the space, it becomes increasingly difficult to learn more. Sleep helps you clean out the junk that is filling up your brain,” she says. Cirelli and her colleagues say that an important function of sleep is to clear away unnecessary “noise” to ready the brain for new learning.
There are many other health benefits to proper sleep, including the digestive, cardiovascular, limbic (emotions) and immune systems. School jurisdictions across the country have responded to the research on sleep and its effect on learning with changing their schedules — schedules that may have been originally set for gas and bus efficiency. But for a more efficient educational process, with well-timed sleep and school schedules, the research clearly points to a re-set.
Deborah Wood is a child development specialist in Annapolis. She holds a doctorate in Human Development from the University of Maryland at College Park and is founding director of the Chesapeake Children’s Museum. Long time fans and new readers can find many of her “Understanding Children” columns archived on the Chesapeake Family Magazine website. You can find her online at drdebbiewood.com.
What do you think? Leave your thoughts in the comments or submit a question to Dr. Debbie at Betsy@jecoannapolis.com