Most people know the term circadian rhythm for its influence on sleep. However, there’s much more to this sophisticated timekeeping system than first meets the eye. To find out what you need to know, keep reading.
When talking about the body’s circadian rhythm, it’s common to assume we’re referring solely to the internal process that helps us sleep. And while it’s true that a healthy circadian rhythm supports restful sleep, there are actually dozens of 24-hour “rhythms” encouraging processes all over the body.
Stimuli such as exercise, social activity, and temperature all play a part in influencing our body’s circadian rhythms. Still, the most influential factor is light, meaning many bodily processes function in unison with the day and night cycle. Circadian rhythms don’t, however, act entirely based on environmental cues. To get started, they need a little help and guidance from your body’s biological clock.
Circadian rhythms help the body know when to eat, sleep, and wake. These 24-hour cycles are controlled by the body’s biological master clock located in a part of your brain called the hypothalamus.
Also referred to as the suprachiasmatic nucleus (SCN), the master clock reacts to periods of light exposure (via the retina), using it as a cue to facilitate sleep and waking, release hormones, activate the digestive system, and much more. Your body will naturally try to align its various circadian rhythms with the activation of the master clock, including the circadian rhythm responsible for regulating our sleep-wake cycle.
Thanks to your circadian rhythm, for the most part, your body will try to follow a strict schedule when it comes to waking and sleeping. However, this 24-hour cycle isn’t fixed, as subtle differences in your biological clock help to define the start and endpoint of your rhythms. Some people might be slower to respond to light exposure, meaning their biological clock has them waking later than usual, while others are early risers.
The body’s sleep-wake cycle is not only one of the clearest examples of a circadian rhythm, but the one most are familiar with. Below is a typical example of how the average circadian rhythm impacts the sleep-wake cycle:
• 7:00–9:00: Light from the rising sun activates your master clock, which in turn tells the circadian rhythm it’s time to start its 24-hour cycle. Your body temperature rises, and levels of cortisol increase to help with alertness.
• 9:00–13:00: The waking process continues as light exposure increases, and hormone levels stabilise. Several other circadian rhythms are activated, including hunger and digestion.
• 13:00–17:00: Once your energy levels peak, your body begins the slow decline into sleep. Melatonin, a hormone crucial to facilitating sleep, starts to build from midday. It’s not uncommon to hit a mid-afternoon slump in energy levels as a result.
• 17:00–23:00: As the sun sets, your energy levels continue dropping as melatonin levels spike. The body is ready to sleep; a reaction triggered by the absence of light.
• 23:00–7:00: All being well, you should be sound asleep!
The process outlined above is an “ideal” example of a sleep-wake cycle, as determined by your circadian rhythm and a typical biological clock.
Sleep disorders can occur from a fault in your body’s internal clock or a prolonged misalignment between your circadian rhythm’s 24-hour cycle and the environment. Circadian sleep disorders, such as delayed sleep phase disorder (DSP), jet lag disorder, shift work disorder, and irregular sleep-wake rhythm, usually involve at least one of the following:
• Difficulty falling asleep
• Trouble staying asleep through the night
• Waking early
• Struggling to feel rested even after sleep
Remember, the body will always try to sync itself with the day and night cycle because of how your biological clock reacts to light exposure. Going against this natural state will nearly always cause a sleep issue or circadian rhythm disorder.
We mentioned earlier that circadian rhythms aren’t fixed, and naturally shift as you get older or because of lifestyle factors. While it’s true that every person’s circadian rhythms will be slightly different, you’ll want them as closely aligned to your master clock as possible.
Unfortunately, your circadian rhythm cannot skip certain phases or extend itself. It exists solely to complete actions based on a 24-hour cycle. We’ll explain the implications of disrupting this cycle shortly; but before we do, here are some common scenarios that can cause problems:
• Shift work: Working irregular hours throws your body’s circadian rhythm into disarray. Sleeping during the day and working at night go against what your body thinks should be happening, and can increase the risk of health problems.
• Time zone changes: Travelling through multiple time zones in a short period causes serious issues with your circadian rhythm. While you can adjust to a new time zone, the body is slow to do so, and you’ll experience fatigue or excessive daytime tiredness during the transition.
• Health conditions: Certain health conditions can disrupt your body’s natural circadian rhythm. For example, blindness can prevent SCN genes from appropriately reacting to light. The body will still follow a 24-hour cycle, but it’s in a constant state of flux, shifting back and forth by hours or minutes.
If you’re experiencing trouble falling or staying asleep, waking early, or excessive daytime tiredness, then it might be time to try to reset your circadian rhythm using the following techniques:
• Manipulate lighting: Light exposure is crucial to a healthy circadian rhythm. As such, careful manipulation can get your circadian rhythm back in sync with the environment. Sleeping in total darkness, combined with exposure to natural light when you wake, is a strong indicator that your body should begin its 24-hour circadian cycle.
• Try fasting: Digestion and metabolism go hand in hand with your sleep-wake cycle, as your body uses cues from the digestive system to reinforce its circadian rhythm. Fasting is a simple way to control meal times, which helps the body synchronise internal processes with external cues.
• Wake up at the same time: Your body cannot skip phases of its circadian rhythm, so you need to ensure it has the time it needs to complete a full 24-hour cycle. Going to bed and waking up at the same time directly supports this need and stabilises the release of sleep hormones.
• Supplement melatonin: The sleep hormone melatonin helps to prepare your body for sleep. However, factors such as artificial light from electronic devices can disrupt the body’s natural levels. Taking melatonin supplements is a practical short-term strategy for reinforcing a balanced circadian rhythm.
• Regular exercise: Exercise is another activity the body uses to help regulate its circadian rhythm. Combined with the health benefits of aerobic exercise, staying active helps you ward off disease and get the rest you need.
Once you’ve reset your circadian rhythm, it’s far better (and much less work) to maintain it than to worry about resetting it every few months. With that focus in mind, below are a few tips for keeping your circadian rhythm healthy:
• A protein-rich breakfast: Not only is protein an essential building block for cells, but it provides the strength and energy we need to go about our day. Try to consume a high-protein food source with your breakfast roughly 1–2 hours after you wake.
• Manage stress levels: We mentioned earlier that the body uses the neurochemical cortisol to help you feel more alert in the morning. Typically, levels diminish throughout the day, but stress has the opposite effect, causing cortisol production to increase. Managing stress keeps cortisol spikes under control and helps to maintain a balanced circadian rhythm.
• Sleep in darkness: Light is the single biggest activator of the biological clock that helps to regulate circadian rhythm. Therefore, controlling your exposure to light is one of the most effective ways to keep your circadian rhythm healthy. As such, consider blackout blinds or using a eye mask when you sleep.
CBD's potential influence on circadian rhythms is an interesting one. We know that the endocannabinoid system (ECS) plays a fundamental role in balancing the needs of different systems and processes, including functions linked to sleep, appetite, and mood.
By extension, it’s possible that CBD could also prove influential due to its proposed effect of the ECS, something initial studies appear to agree with. A 2019 study observed CBD to upregulate and downregulate specific cells in the suprachiasmatic nucleus—the master clock in your hypothalamus. However, the extent of the interaction, and how the modulation of critical cells could support a healthy circadian rhythm, remains under investigation.
Regardless of how you choose to maintain a balanced circadian rhythm, the key factor is listening to your body. Find a sleep schedule that fits your lifestyle and your biological clock. The closer you can sync your daytime routines to when your body naturally wakes, the better you’ll sleep at night.
Interested in using natural sleep supplements or CBD to help balance your circadian rhythm? Why not browse the Cibdol store for a complete selection of high-quality products. If you’re still fascinated by the concept of sleep, sleep cycles, and sleep hygiene, visit our CBD Encyclopedia to learn more.
 Circadian rhythms. National Institute of General Medical Sciences. https://www.nigms.nih.gov/education/fact-sheets/Pages/circadian-rhythms.aspx. Published 2021. Accessed January 11, 2022. [Source]
 Schroeder AM, Colwell CS. How to fix a broken clock. Trends in pharmacological sciences. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856231/. Published November 2013. Accessed January 11, 2022. [Source]
 Tahara Y, Aoyama S, Shibata S. The mammalian circadian clock and its entrainment by stress and exercise. The journal of physiological sciences : JPS. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5138246/. Published January 2017. Accessed January 11, 2022. [Source]
 Lewis P; Oster H; Korf HW; Foster RG; Erren TC; P. Food as a circadian time cue - evidence from human studies. Nature reviews. Endocrinology. https://pubmed.ncbi.nlm.nih.gov/32055029/. Published 2020. Accessed January 11, 2022. [Source]
 Zou S, Kumar U. Cannabinoid receptors and the endocannabinoid system: Signaling and function in the central nervous system. International journal of molecular sciences. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5877694/. Published March 13, 2018. Accessed January 12, 2022. [Source]
 A; LGDCMLB. Cannabidiol affects circadian clock core complex and its regulation in microglia cells. Addiction biology. https://pubmed.ncbi.nlm.nih.gov/30307084/. Published 2019. Accessed January 11, 2022. [Source]