7 Factors That Affect Your Natural Sleep-Wake Cycle

Experiencing a refreshing night’s sleep can be a wonderful start to your day, leaving you feeling rejuvenated, attentive, and prepared to tackle whatever lies ahead. Unfortunately, for a significant number of individuals, achieving restful sleep can be an elusive goal. Approximately 70 million Americans contend with persistent sleep issues, as reported by the Centers for Disease Control and Prevention (CDC). While these sleep challenges may stem from various factors such as underlying health conditions, sleep disorders, insufficient physical activity, or risky lifestyle choices, for many individuals, the root cause could be a disruption in their circadian rhythm.

What Is Your Circadian Rhythm?

The circadian rhythm serves as the body’s internal timekeeper, primarily responsible for regulating periods of alertness, wakefulness, and sleepiness. It works to synchronize and consolidate periods of wakefulness and sleep, ensuring that your periods of being awake occur together and similarly for sleep. Disruptions to this circadian rhythm and sleep-wake cycle can lead to significant sleep-related issues, including insomnia, mental health challenges, metabolic disturbances, cognitive difficulties, and more.

Dr. Patricia Pinto-Garcia, MD, MPH, who serves as a medical editor at GoodRx, explains that newborns do not possess a fully developed circadian rhythm, and it matures over time. This explains why newborns frequently cycle between periods of sleep and wakefulness throughout the day. Without a well-established circadian rhythm, individuals would experience a schedule resembling that of a newborn, with frequent bouts of sleepiness and wakefulness. Such a pattern would make it nearly impossible to engage in any meaningful activities, as one might fall asleep during work, while watching a movie, or even during a long drive.

External factors that can influence an individual’s circadian rhythm are known as “zeitgebers,” a German term that translates to “time-giver,” as explained by Dr. Pinto-Garcia. While adhering to a consistent sleep schedule is the most effective way to respect one’s circadian rhythm, there are several other less obvious zeitgebers that may be disrupting your ability to achieve a restful night’s sleep.

Top Factors That Impact Your Circadian Rhythm

Exposure to excessive evening light can disrupt the process of winding down for sleep. Our brains require dim light to prepare for sleep, enabling the natural production of melatonin, a hormone that induces sleepiness. Shelby Harris, PsyD, DBSM, a clinical psychologist and sleep specialist, points out that if you are exposed to bright sunlight and then immediately attempt to go to bed, you may find it challenging to relax and fall asleep at an earlier hour. This applies similarly to blue light, which is emitted by electronic devices such as phones, tablets, TVs, and computers.

To counteract this, Harris suggests being mindful of your exposure to nighttime light and electronics. Consider using blackout curtains or a sleep mask if your room is still exposed to light at bedtime. Additionally, it’s advisable to limit electronic device usage 30 to 60 minutes before bedtime to facilitate the process of winding down.

Insufficient exposure to morning light can also impact your circadian rhythm negatively. Your circadian rhythm is closely linked to light, with its presence or absence signaling wakefulness or sleepiness, respectively. While minimizing exposure to light is crucial as you wind down at night, the opposite holds true when you wake up. Morning light exposure is vital in establishing your body’s circadian rhythm, effectively resetting your internal sleep clock to signal that it’s time to start the day. Research has even demonstrated that as little as five minutes of morning light exposure can advance this internal clock, kickstarting your day.

Dr. Harris advises that natural light is more effective than indoor light for this purpose. However, if you cannot access natural light or lack a window to sit near in the morning, you can turn on all the lights in your surroundings to help awaken your brain and body. This can be achieved by having breakfast outdoors, taking a brief walk around your neighborhood, or merely sitting by an open window while engaging in activities such as reading or meditation.

Another factor that can disrupt your circadian rhythm is excessive caffeine consumption, especially later in the day. While many individuals rely on a cup or more of coffee in the morning to boost energy and alertness, consuming too much caffeine later in the day can leave you feeling wired and disrupt your body’s ability to recognize that it’s time to wind down for sleep. Dr. Pinto-Garcia suggests that if you experience difficulties falling asleep at night, restlessness, or excessive daytime fatigue, it may be prudent to limit caffeine intake to the morning hours or consider eliminating it altogether. If you still wish to enjoy a beverage later in the day, opting for tea, which typically contains less caffeine than coffee or soda, may be a more suitable choice.

Exercise timing plays a significant role in the functioning of your circadian rhythm, your body’s internal clock regulating sleep-wake cycles. Engaging in physical activity offers numerous health benefits, including improving sleep quality and duration. However, the timing of your exercise sessions can influence your circadian rhythm.

Dr. Pinto-Garcia explains that exercise acts as a cue to your body, signaling that it’s time to remain awake. Aerobic exercises, such as running, swimming, and biking, stimulate the earlier release of melatonin, a hormone involved in sleep regulation. This can advance your circadian rhythm, causing you to feel more awake and alert. Moreover, early morning outdoor exercise exposes you to natural light, which can further stabilize your circadian rhythm and make it easier to fall asleep.

However, it’s essential to consider your natural circadian rhythm when planning your exercise routine. Some individuals naturally have advanced or delayed circadian rhythms, which is entirely normal and not a medical condition. If you are a night owl or an early bird due to your inherent circadian rhythm, there is no need for concern, provided your natural rhythms do not significantly disrupt your sleep or daily activities.

If you discover that you feel overly energized and wired after late-day or early evening workouts, it may be beneficial to shift your exercise routine to the morning or early afternoon. This adjustment can help ensure that your circadian rhythm functions optimally and facilitate a quicker transition to a state of relaxation and sleep. However, if you do not experience difficulty winding down after an evening workout, there is no need to change your exercise routine; consistency with what works best for you is key.

In cases where sleep patterns are disrupted due to factors such as irregular work schedules (e.g., night shifts), caring for a newborn, or occasional all-nighters, it’s essential to approach changes gradually. Abruptly altering your sleep-wake schedule can lead to sleep problems. Dr. Harris recommends a more gradual adjustment, starting with a consistent bedtime and wake-up time. Over the course of one to two weeks, adjust your sleep-wake schedule earlier by 15 minutes every one to two days until it aligns with your desired sleep schedule.

For situations where you need to quickly readjust your schedule, such as after traveling to a different time zone, melatonin supplements can be helpful. Taking 3 to 5 mg of melatonin one hour before your intended bedtime can assist in resetting your internal clock. However, melatonin should be used sparingly and only when needed, not as a nightly sleep aid.

When Should You Talk to a Doctor or Sleep Specialist?

Experiencing occasional difficulties with falling asleep or staying asleep is a common occurrence. However, if you find yourself struggling with sleep-related issues for an extended period, particularly beyond three weeks, and you begin to notice symptoms such as difficulty concentrating or severe daytime drowsiness, it is advisable to seek professional help. Consulting with a healthcare provider or a sleep specialist is essential in such cases, as they can provide a thorough evaluation, diagnose any underlying sleep disorders, and offer guidance tailored to your specific symptoms.

Failure to address persistent sleep concerns can lead to more severe consequences, including an increased risk of sleep deprivation. Dr. Pinto-Garcia emphasizes the potential health risks associated with chronic sleep deprivation. These risks encompass a range of medical conditions, such as heart disease, kidney disease, diabetes, stroke, and depression. Additionally, sleep deprivation can elevate the likelihood of accidents and injuries, both in occupational and domestic settings.

To mitigate these risks and improve your overall sleep health, it is crucial to consult with sleep specialists who possess expertise in circadian rhythm management and sleep optimization. These specialists can offer personalized strategies and interventions to align your sleep patterns with your circadian rhythm and promote healthy and restorative sleep. Addressing sleep concerns promptly and seeking professional guidance can contribute significantly to your overall well-being and reduce the potential health risks associated with chronic sleep deprivation.