Did you know there’s a reason behind teenagers’ “up all night, sleep all day” lifestyle? Or that when you’re in your 30s, your internal clock reverts back to your childhood? While you have a unique chronotype (“early bird” or “night owl”), which determines your default circadian rhythm, there are easily predicted shifts within your default rhythm that occur throughout your lifetime.

Sleep During Childhood

When you’re born, you don’t have an established circadian rhythm yet. You haven’t had a chance for your chronotype to influence your body because those systems in your brain show up later in development. Babies’ bodies need to prioritize growth over a full night’s sleep, which means children (and their parents) have to adapt to a faster feeding cycle.

If you ever feel like babies don’t care about time, you’re right! They eat, sleep, nap, and repeat, regardless of the time of day.

After a couple of months, babies begin to follow a schedule and sleep with a more predictable pattern. At this phase, individuals start to express their chronotype.

However, all kids tend to wake on the earlier side, until puberty and sex hormones delay our natural circadian rhythm.

Sleep During Teenage Years

As we all remember from the awkward sex-education movies in school when puberty hits you may notice some changes. However, those videos leave out one key, less-sensational change: you may start sleeping when you didn’t before.

As sex hormones increase, they push your internal clock later and give rise to the stereotype of the lazy teenager. Teenagers are not inherently lazy, but they are socially jetlagged due to a mismatch between their body’s delay in their daily rhythm and schools’ early start times. Their bodies want to stay up late and sleep in, but the reality is they lose out on sleep which impacts their performance and health.

Sleep During Adulthood

Once we are out of school, we still have social jetlag from the demands of work, but our bodies are no longer fluctuating through development. As an adult, you become more familiar with your natural patterns.

As the rush of hormones from your teenage years begins to let up, your circadian rhythm trends earlier again, so that by your 30s you are more closely approximating your childhood schedule.

Sleep During Senior Years

Internal clocks start to struggle as you age. Sleeping and daily routines become more stressful as joints age. You may also spend more time indoors, especially in assisted living situations.

This creates a vicious cycle where you’re restless and awake at night due to the physical inability to be active while the sun is out. Without that balance, your circadian rhythm becomes desynchronized–accelerating aging and making sleep less restorative.

Things to Keep in Mind

Your rhythm is always changing–stay up to date. Wearables like Oura allow you to discover your chronotype and determine whether or not your lifestyle aligns with your body’s needs. By understanding what forces your circadian rhythm out of alignment, you can adjust your actions to keep your internal clock running smoothly.

Whether it’s a new job, an addition to the family, or retirement, ensure that you take the time to discover and listen to your internal rhythms.