Each day, every single person on Earth lives according to a set schedule. It starts when you wake up and ends when you go to sleep, starting again the very next day. Changes to this normal routine can and often do happen, but it’s easy to get back on track again as long as you keep your routine going.
While we all have a unique daily routine of tasks and goals, our body’s internal clock, specifically our circadian rhythm, can greatly impact our day-to-day regime. You may hear a lot about this internal schedule and how important it is to your health— but what is your circadian rhythm, and what does it do? There is a lot more to it than you may realize, so let’s take a look.
What is a Circadian Rhythm?
Your circadian rhythm is a 24-hour cycle that works within your body’s internal clock. Both your circadian rhythm and your internal clock are controlled by the Suprachiasmatic Nucleus, which is found in a section of your brain called the hypothalamus. Your circadian rhythm maintains many of your body’s systems, including your digestive system, your endocrine system, and your immune system.
Your circadian rhythm isn’t the same as your biological clock though, rather, it’s a subset of your biological clock. Your biological clock dictates your circadian rhythm in accordance with environmental and personal changes, such as changes in the season, your age, or even your cell phone usage.
How Do Circadian Rhythms Affect Sleep?
Your circadian rhythm is key to a good night’s sleep, because of its best-known function— regulating and maintaining your sleep-wake cycle. Your circadian rhythm is primarily influenced by natural light from the sun. Sunlight triggers your circadian rhythm, causing it to produce less melatonin in order to wake you up as the sun rises. As the sun again dips below the horizon and the night takes over, your circadian rhythm signals your brain to produce more melatonin to help you sleep.
Melatonin— often known as the “sleep hormone”— is produced in your brain’s pineal gland, and is a vital component not only for your sleep but also for your overall health.
What Happens When Your Circadian Rhythm is Out of Sync?
A disruption in your circadian rhythm can be problematic. Circadian rhythm disruption can be caused by a number of factors, such as:
- Time changes as a result of daylight savings time
- An irregular sleep schedule or changes to your normal sleep habits
- Blue light exposure from electronic devices inhibiting melatonin production
- Jet lag
While your circadian rhythm is key to healthy sleep, good sleep is also important for maintaining a healthy circadian rhythm. Circadian rhythm disruption can cause or contribute to sleep problems such as sleep deprivation and daytime sleepiness, as well as sleep disorders like shift work sleep disorder, delayed sleep phase disorder, and even obstructive sleep apnea.
Both sleep disorders and circadian rhythm abnormalities can prevent you from getting the restful REM sleep you need to feel awake and refreshed in the morning. You may be unable to fall asleep at your normal bedtime, or your body may even try to sleep when you need to be awake as your internal clock tries to correct itself.
One particular sleep disorder that can be worsened by a circadian rhythm disorder is sleep apnea.
Related: Circadian Rhythm Sleep Disorders
Circadian Rhythms and Obstructive Sleep Apnea
Obstructive sleep apnea (OSA) is a very serious sleep disorder where your airways become blocked while you sleep, causing difficulty or pauses in breathing. Obstructive sleep apnea is often associated with equally serious comorbidities including:
- Heart disease and high blood pressure
- Mental health disorders including depression or anxiety
Obstructive sleep apnea can also lead to the dysregulation of your circadian rhythm, which can exacerbate your symptoms and make it even harder to get the healthy sleep you need.
According to a study published by the Annals of the American Thoracic Society, your circadian rhythm can affect the outcomes of many common but serious health conditions like OSA, sepsis, and even cancer. Circadian misalignment can not only impact the severity of these conditions, but it can also impact how likely you would be to survive them.
The study notes that the impact of the circadian rhythm on OSA symptoms is unclear, but it may influence apnea occurrence and duration. Notably, prolonged apnea events were found to happen much more frequently in the early morning than they were in the evening or afternoon. This corresponds with the circadian rhythm’s shift in the morning, which wakes you up and prepares you for the day.
A study published by the journal Diagnostics found that obstructive sleep apnea can lead to the dysregulation of your circadian rhythm. The study has found that circadian rhythm disruption could worsen OSA-related outcomes— such as cardiovascular health and cognitive function— even if you don’t have sleep apnea.
More research is needed to understand how circadian rhythms and obstructive sleep apnea can affect each other, but one thing is clear— a good night’s sleep is vital to maintaining a healthy lifestyle and sound circadian rhythm.
Related: What Makes Sleep Apnea Worse? 8 Things to Watch Out For
How to Keep Your Circadian Rhythm Healthy
Keeping your circadian rhythm healthy and on track can be as easy as making healthy lifestyle choices. If you’re struggling to get a good night’s sleep, consider giving some of these solutions suggested below.
- Follow a Consistent Sleep Schedule. Going to sleep at the same time every night and waking up at the same time every morning is one of the best things you can do for healthy sleep and a healthy circadian rhythm. By following the same schedule every day— including weekends or days with less strict schedules— you can train your body to know when to sleep and when it’s time to wake up. A consistent and stable sleep schedule is perhaps the most important factor in maintaining a healthy circadian rhythm.
- Avoid Blue Light Exposure before Bed. While the blue light from the sun can help you wake up and prepare for the coming day, the blue light emitted by electronic devices like cellphones, computers, and TVs can hinder the necessary melatonin production you need to fall asleep on time each night. To avoid this, stop using your electronic devices at least an hour before bedtime. Many phones have blue light filter settings that may reduce eyestrain and block your phone from emitting blue light altogether, though there are some questions in the research about the overall effectiveness of those filter settings.
Alternatively, you can also use blue light blocking glasses or screen protectors from companies like Occushield or Swanwick, which help your brain produce the melatonin necessary for a good night’s sleep, even if you’re using your devices before bedtime.
- Exercise: It’s hard to overstate the benefits that regular exercise has on the human body. At least 30 minutes of daily moderate exercise can keep you physically fit, help prevent sleep apnea, and support your circadian function.
- Get Tested for Sleep Disorders: A sleep disorder like sleep apnea, insomnia, or circadian rhythm abnormalities can make it impossible to get a good night’s sleep— especially since many people don’t even know they have one. If you or your bed partner notice symptoms like loud snoring, taking 30 minutes or more to fall asleep each night, or waking up tired even after a full night’s sleep, those are signs that you need to be tested for a sleep disorder.
Your circadian rhythm is a key part of not only a good night’s sleep, but in your overall health as well. In short, if you take care of it, it will take care of you.
If you’re struggling to get a good night’s sleep, contact us at the Sleep Centers of Middle Tennessee. We can help you make sense of your symptoms and help you get back to the restful, healthy sleep you need to be at your best.
Truong, Kimberly K, et al. “Timing Matters: Circadian Rhythm in Sepsis, Obstructive Lung Disease, Obstructive Sleep Apnea, and Cancer.” Annals of the American Thoracic Society, 21 Apr. 2016, www.atsjournals.org/doi/10.1513/annalsats.201602-125fr.
Koritala, Bala S C, et al. “Circadian Biology in Obstructive Sleep Apnea.” Diagnostics (Basel, Switzerland), MDPI, 13 June 2021, www.ncbi.nlm.nih.gov/pmc/articles/PMC8231795/.