Do teenagers have a different circadian rhythm?
This is a thought pretty much every parent has when their kids reach the teen years - why does my kid not want to go to bed before midnight? Or else this - why do they become a vampire, staying up late into the night and sleeping during the day? Are they just wanting to be a defiant teenager, are they really a vampire... or is there a biological reason?
The rhythms of our body are known as circadian rhythms. Many are intrinsically connected to our external environment, with light being the dominant trigger. Receptors in our eyes register the level of light in our environment, activating a cascade of functions in our body. Today, in our modern lifestyle, we have two sources of light - natural, from the sunlight, and artificial, from light bulbs and electronic devices. However, our eyes don’t know the difference. Whatever the light type (natural or artificial), the message to the brain is - it’s still light therefore we should be awake and alert.
For more about the mechanics of our circadian rhythm, read our other articles:
Now with an understanding of the basics of the circadian rhythm, are we all marching to the beat of the same drum, do we all follow the same daily pattern?
To some degree we do, because our circadian rhythm is tied to the daily rhythms of nature - awake and alert when there is sunlight, and sleepy when it’s dark.
But there are times in our lives when the rhythms are slightly different and one such time is during the teenage years.
Why are their sleeping habits different?
We all know about the nocturnal sleeping habits of teenagers - going to bed in the early morning hours, waking up late in the day, missing the whole morning, barely seeing the sunlight, then doing it all again the next day. Much to a parents dismay, teenagers seem to have the energy to stay up until 1am in the morning yet don’t have the energy to empty the dishwasher in the morning or perform an even simpler task of brushing their teeth...
If this sounds familiar, there are biological mechanisms at play causing teenagers to follow a slightly different sleep pattern. Don’t tell them this though…
Melatonin is produced daily by the pineal gland, located in the hypothalamus of the brain. The basic process of production is as follows - tryptophan (from protein we eat) is converted to serotonin, then again converted eventually to melatonin. Activating this series of steps is light exposure, and conversely, lack of light activates the secretion process. Even though melatonin is commonly called the sleep hormone, a more apt name would be the darkness hormone, due to secretion of it only occurring when darkness is registered by the eyes.
Timing of the secretion stage for adults is typically around 9pm, seasonally dependent (slightly pushed back during summer with the sun setting later). In teens melatonin secretion occurs 2-4 hours later. The shift in this timing coincides with puberty, the peak age of hormone development and melatonin being a hormone is affected like most others.
Why are they so sleepy in the morning?
The length of time that melatonin is secreted into the bloodstream is pretty consistent, but now with a later start time, closer to midnight, this means that it continues throughout the morning. Let’s compare the timing and length of the circadian rhythm of a typical adult, to a typical teenager.
Adult: Melatonin levels start to rise around 9pm, reach a peak between 2-4am, and secretion stops around 7.30am Total length of time is around 10 hours 30 mins.
Teenager: Melatonin secretion is delayed, some starting as early as 11pm and others as late as 1am, reaching a peak between 4-6am or 8am for the later starters, and secretion stopping at 9.30am or later, if their cycle is closer to the 4 hour difference. Same total length of time, but this explains why teens wake up in a state of fogginess. Waking up around 7am, or earlier for school, is not long past their peak melatonin point. This explains why it’s so hard to wake a sleeping teenager and why they seem barely able to function as a human being first thing in the morning. Their bloodstream is flush with melatonin.
What should I do to help my teenager get as much sleep as possible?
To support their growing bodies and developing brains, teenagers need around 8-10 hours of sleep daily, compared to 7-9 hours for adults. According to recent research of 800+ adolescents, sleep is critical, clearly leading to better overall health. The study found important markers of cardiovascular and metabolic health evident in teens who experienced longer sleep times and a higher quality of sleep. Specifically, the more sleep and higher the quality led to lower systolic blood pressure, higher HDL cholesterol (the good cholesterol), better insulin resistance, and a smaller waist circumference. Unfortunately the study also found that a third of teenagers are getting less than 7 hours of sleep a night and sleep quality is poor.
Knowing that your teen is likely to be biologically predisposed to a later sleep pattern, how can you help them reach their required level of sleep hours? Even with a later melatonin cycle, it’s important to not exacerbate this further by exposing them to artificial blue light at night. The last thing they need is more reasons for their brain to stay alert and active. Blue light at night suppresses the release of melatonin to an even later hour, adding more time to their delayed schedule.
Now it’s probably unlikely that you can convince your independently minded teenager to shut off all electronic devices and switch off light bulbs once it’s dark, but there is an alternative that could be acceptable (as long as you don’t lecture them about it…) - get them a stylish pair of blue light blocking glasses to wear as soon as the sun sets, until they finally decide it’s time to sleep.
Our Night lenses were expertly developed to effectively block 100% of blue light, protecting their eyes from being exposed to the high energy wavelengths from devices and light bulbs that is tricking their brain into believing it needs to stay awake and alert long past the healthy hour.
But it’s still important to educate your teen on healthy sleep habits, which includes switching off devices at an appropriate time and not over activating their brains at night time.
How long does this night owl behavior last?
The shift back happens at around the age of 20 so the biological reason for a delay in sleepiness lasts for around 6-8 years. At this age, the reason for staying up late becomes psychologically driven (all the exciting stuff happens at night so I need to stay out late…) rather than physiological.
But the need to block blue light at night is just as relevant at the young adult stage, as it was during the teen years. We constructed our glasses with the highest quality materials available so they will last beyond the teenage years (Italian acetate frames for durability, German-engineered steel for strength, and scratch resistant CR39 lenses) provided they don’t misplace them in that dirty clothes pile that seems to be moving...