Buzz
While it may feel natural for humans to know when to sleep, wake, or eat, these vital cues are largely governed by our circadian rhythm. This internal clock, which operates on a roughly 24-hour cycle, significantly influences our physical and mental health. It interacts with various organ systems and even individual cells. Discover how your circadian rhythm functions and learn how to align with and support your unique sleep-wake cycle for optimal well-being.
Anastasiia Bidzilia/Getty ImagesWhat Is Your Circadian Rhythm?
Christina Pierpaoli Parker, PhD, a licensed clinical psychologist with board certification in behavioral sleep medicine, describes the circadian rhythm as the body’s “central pacemaker” responsible for “regulating the timing of our sleep.”
Every individual is born with the innate ability to develop a circadian rhythm. This rhythm typically begins to form in humans around two to three months of age, which clarifies why newborns often lack a clear distinction between day and night in their sleep patterns. Once established, your circadian rhythm controls cycles of wakefulness and drowsiness by reacting to external cues, especially changes in light. As a result, darkness triggers sleepiness, while daylight promotes alertness.
In the absence of a circadian rhythm, human sleep would become chaotic, with no clear differentiation between day and night. Beyond erratic sleep patterns, we would also "fail to optimize energy use and the body’s internal physiological processes," as highlighted in a research study on physiology and circadian rhythms.
How Does It Affect Your Health and Life?
Your circadian rhythm influences your alertness, drowsiness, hunger, and even body temperature. “Our understanding of circadian rhythms reveals that the sleep-wake cycle is a fundamental aspect of human health,” states Sudha Tallavajhula, MD, a sleep neurologist and medical director at TIRR Memorial Hermann Neurological Sleep Medicine Center. “Every other organ system operates in sync with periods of wakefulness and sleep.”
Disruptions or interference with your circadian rhythm can trigger a cascade of health-related effects across your body’s essential systems. These include your immune system, digestive system, various hormone systems (such as reproductive and endocrine), and cardiovascular systems, among others.
Dr. Tallavajhula emphasizes that crucial bodily functions synchronize with the day-night cycle, all thanks to our circadian rhythm. “For instance, your kidneys decrease urine production at night to prevent sleep disturbances,” she notes. “Similarly, hormones like steroids, which support wakefulness, are reduced during sleep.”
Why Does Understanding Your Circadian Rhythm Matter?
High-quality sleep is undeniably vital for overall health, affecting everything from memory and mood to immune function and blood pressure. Ignoring the cues from our circadian rhythm can lead to significant consequences. Pierpaoli Parker points out that sleeping at a “suboptimal circadian time” can disrupt sleep quality and its fundamental structure, known as sleep architecture.
Pierpaoli Parker further explains that such disruptions can heighten the risk of conditions like diabetes, hypertension (high blood pressure), and even cancer. Beyond regulating sleep and eating patterns, our circadian rhythm plays a critical role in maintaining long-term health and preventing diseases.
What Affects Your Circadian Rhythm?
Maintaining a consistent sleep schedule can be challenging. Factors like time zone changes, shift work, and everyday stress can disrupt your circadian rhythm, or internal clock. Even small habits and environmental factors play a role. Pierpaoli Parker highlights that artificial light sources, such as smartphones, computers, and TVs, emit blue light that can interfere with your circadian rhythm. This is why sleep experts often advise limiting screen use before bed.
Genetic conditions impacting the brain or hormones can also lead to circadian rhythm disorders. Consuming caffeine in the evening can delay your natural sleep cycle, so opting for caffeine-free herbal tea instead of coffee or black tea before bed is a better choice. Additionally, excessive light in your room can trick your body into thinking it’s daytime, even at night. Using blackout curtains or a sleep mask can help mitigate this issue.
The Best Ways to Support Your Circadian Rhythm
Although the circadian rhythm is a natural process, you can take steps to support it and align with your body’s sleep-wake cycle. This helps you feel your best and maintain optimal health. Pierpaoli Parker suggests adopting certain lifestyle changes—known as good sleep hygiene practices—to promote a balanced and well-supported circadian rhythm.
- Only head to bed when you genuinely feel sleepy, not just fatigued (e.g., limit naps unless necessary—though they can be beneficial if kept brief and avoided late in the day).
- Maintain a steady wake-up time, even on weekends.
- Aim for 10 to 30 minutes of sunlight exposure after waking up.
- Stick to a regular bedtime routine.
- Enjoy a warm bath or shower before bed (this raises then lowers your body temperature, aiding sleep).
- Choose a book over TV or screens before sleeping.
- Avoid using smartphones, laptops, or TVs in bed.
By establishing a calming bedtime routine and consistent wake-up times, you can maintain a balanced circadian rhythm and enjoy the numerous health benefits it provides.
