Biology Basics: Understanding Your Internal Clock


When it comes to defining the perfect night’s sleep, everyone has a set of criteria. For example, some people may need at least eight hours of shut-eye, whereas others can get by with six or less. Some sleepers may enjoy having a bit of lighting in their bedroom at night, whereas some prefer having complete darkness.

So what explains these different habits? While it may seem like it’s a matter of personal preference, biological features are the ones that determine these sleeping nuances.

Take your body type and weight, for example. Understanding how these factors affect your sleep will help you make informed decisions about your sleep setup. For instance, choosing a firm vs soft mattress shouldn’t be solely about comfort—you should find one that provides the support you need based on your body type.

While your weight and body type should inform your mattress material choice, understanding your circadian rhythm, which influences numerous bodily processes, should dictate many of your routines and lifestyle choices. Why? Because your circadian rhythm directly impacts the duration and quality of the sleep you get each night.

The Role of Your Circadian Rhythm

The circadian rhythm is an internal system that controls the flow of your daily activities. It functions as a component of your internal clock—a function of the brain—to determine the timing of actions, such as sleeping and waking up. The way the circadian rhythm functions varies from one person to another. That’s why some people consider themselves to be “morning people,” whereas others identify as “night owls.”

What Does Your Circadian Rhythm Regulate?

One of the primary functions of the circadian rhythm is to regulate your sleep-wake cycles. For example, when your internal clock detects a source of light, it produces cortisol hormones and orders your body to get up and stay awake throughout the day. When the night falls, it produces melatonin and orders the system to go to sleep.

The circadian rhythm can also regulate blood and cholesterol, which can impact your metabolism and body weight. Research has also found that the circadian rhythm can impact your mental health. When the system is out of sync with the internal clock, this can trigger certain disorders such as insomnia and depression.

What Factors Can Affect or Disrupt Your Circadian Rhythm?

As previously mentioned, understanding how your circadian rhythm works should influence your daily routines. The following factors can misalign your circadian rhythm, making it difficult to fall asleep and stay asleep. By monitoring and altering your behaviors, you can improve your sleep one day at a time.

  • Sunlight– Regular exposure to a natural source of light—the sun—is vital for a healthy circadian rhythm. A lack of natural light can cause a shortage of cortisol levels, making you feel tired or lacking energy.
  • Blue Light Exposure– This type of artificial light is formed by wavelengths given off by everyday electronics such as phones, computers, and TVs. Overexposure to blue light during evening hours may keep you up late into the night and disrupt your natural sleeping pattern.
  • Inconsistency– Inconsistency in your daily routine may cause your circadian rhythm to fall out of whack. An irregular sleep schedule and varied mealtimes can lead to developing a sleep disorder, and those who work night shifts are at greater risk.
  • Travel Across Timezones– If you travel across time zones often, you’re susceptible to developing a jet lag disorder, an advanced form of a circadian rhythm disorder. Especially when traveling for short periods, the internal clock doesn’t get enough time to get used to the new environment, which can cause you to fall asleep and wake up at odd times.
  • Medications– Some medications, such as those used to treat certain mental disorders, may cause you to develop a delayed sleep-wake rhythm. For example, those who take certain medications for insomnia, depression, and bipolar disorder may experience a shift from their regular sleep and wake-up times.

Internalizing Healthy Sleep Habits

With a better understanding of how biology impacts your sleep preferences, perfect sleep setup, and ideal daily routines, you can start making changes that promote restorative sleep.

Remember, your ability to answer your internal clock’s signals is key to a healthy lifestyle. If you feel that your internal clock is out of sync, consider taking concrete steps to take control of your circadian rhythm and sleep-wake cycle.