There is a good reason why many teens stay up until 3 a.m. and sleep in until noon. It is because their circadian rhythms, or internal biological clock in the brain, literally have been put on snooze until their late 20’s.
Circadian Rhythms and Clock Genes
Our bodies are regulated by circadian rhythms, which are 24-hour cycles. We know there are a series of genes, “clock genes,” that are involved in the regulation of circadian rhythms, which interact with the body’s exposure to light. There are many different genes involved in the timing of circadian rhythms whether you are on a 24.6 hour rhythm or 22 hour rhythm. Some of these genes are responsible for keeping you as close to 24 hours as possible. However, our internal body clock is typically slightly longer than 24 hours so we are constantly trying to adjust for the difference in time.
Light Sensitive Genes
There are at least 35 known genes that are light sensitive, but there are also “non-photic” genes that tend to turn on later during development and infancy. These circadian genes regulate a whole host of biological functions such as heart rate, the gut and gastric cycle, and our biological need for sleep. Anyone who has tried to pull an “all-nighter” knows that our bodies have a deep drive for sleep. As a child grows, its body finds a healthy relationship between its internal clock and exposure to light. Our modern lifestyle filled with artificial light, however, creates sleep disturbances that can begin to cause problems for growing bodies
How the Science Relates to Teen Sleep Patterns
Major changes in circadian rhythms occur during adolescence causing night- owl-type behavior. The body clock begins to “phase delay” becoming sleepy at a later time. An adult’s natural biological preference for sleep usually begins around 11 p.m., but in adolescence this drifts to much later times. Eventually, most adults will adjust and grow out of this teen sleep behavior. A biological clock that is not on a normal light/dark cycle becomes a risk factor for the development of depression. It is no coincidence that the greatest risk for the onset of depression is during the teens and years surrounding young adulthood when young bodies are transitioning to adulthood in many ways. Unfortunately, the peak onset of depression and bipolar disorder occurs between 15 – 24 years of age, and this may be linked to the problematic sleep cycles of teens. In the last 25 years this sleep gap has worsened as children are going to bed at least an hour later than they did a generation ago. “I’m tired, Mom,” may have an underlying biological basis.