Zeitgebers & the Circadian Rhythm: Working With Environmental Cues to Encourage Healthy Sleep Habits

Space may be the final frontier, but bedtime is not far behind. Using zeitgebers to work with your child's circadian rhythm holds a key to conquering the battle.

Many parents spend countless nights on exploratory journeys, devising ways to convince their children that sleep is a good idea.

In nature, animals fall asleep naturally and easily. Their bodies respond to the environmental cues around them, such as the shift in temperature and change in light, that signal to their bodies that it’s time to rest. Until recently, the same has been true for humans as well. It’s easy to forget that the industrial revolution, the dawn of modern life as we know it, wasn’t really that long ago. Even in 1925, less than 100 years ago, only half of homes in the U.S. had electricity.

Our bodies are still deeply conditioned to take note of the environment, and increase sleepiness or alertness accordingly. However, we’ve outfitted our homes with many comforts that interfere with these signals from nature.

Blue Light and Sleeplessness

The light emitted from most light bulbs and screens is a blue light that is received by the retina in such a way that it signals to stop the flow of melatonin, which naturally increases as light lowers, generating a sleepy feeling. Additionally, while it may sound counterintuitive, keeping the house too warm actually has a tendency to keep the brain awake, because the body associates warner temperatures with daytime, and cooler temperatures with a lack of sunlight, and therefore nighttime.


These environmental cues are called zeitgebers, which translates as “time giver”, or “synchronizer”. While light is by far the most powerful example, there are other common zeitgebers as well, including exercise, social interaction, and patterns of eating and drinking.

So how can this help address the age-old statement, “I’m not tired!”? It’s simple, really. The body’s sleepiness and wakefulness are governed by a combination of zeitgebers, or external cues, and the circadian rhythm, the body’s internal clock that naturally follows a roughly 24 hour cycle, mirroring that of the earth’s trip around the sun. Strengthening a child’s circadian rhythm and limiting zeitgebers that cue alertness help to signal on a neurological level that the time for sleep is approaching.

In addition to trading blue-tinted light bulbs for warmer toned ones, limiting screen use later in the day is a great way for children’s (and adults’) bodies to understand that bedtime is approaching. Keeping a buffer of at least an hour between show time and bedtime reduces stimulation and allows melatonin to naturally do its work.


Getting outside during the day also has its benefits. Absorbing sunlight and creating vitamin D signal to the body that it’s daytime, and thus reinforces the circadian cycle. If you are particularly concerned about blue light, there are “blue blocking” sunglasses that will further reduce such interference.

Above all, creating a consistent routine before bedtime allows children to understand and participate in a ritual that gets them mentally and emotionally prepared for sleep. Something as simple as reading a bedtime story at the same time every night becomes a habit that’s ingrained in the body, and thus encourages a restful state for children and parents alike. Reducing light, cooling off the room, and incorporating routines that tell the body that sleep is happening at the same time, in the same way, every night, will help kids to get more rest and have a better day ahead.

For more insight into healthy sleep routines for children, listen to our podcast, Mom Driven, Doctor Aligned.

Published on: March 07, 2020
About the Author
Photo of Alan Greene MD
Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.
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