CBD & the Circadian Rhythm
You must have heard about the “body clock”. There’s an entire network of these molecular clocks distributed across your organs and cells that are programmed to follow a 24-hour cycle. You won’t hear them tick but they are running in the background non-stop.
Their movement triggers physical and mental changes known as the circadian rhythm. Your circadian rhythm tells your body when to be active and inactive through the day, causing body temperature, appetite, and energy levels to rise and fall at consistent times. From sleeping to eating, these clocks regulate all your repetitive biological processes.
All the biological clocks in the body are wired to a master clock which sits in the hypothalamus of the brain and calls all the shots. It is attuned to environmental cues, especially light. Nerves linking the master clock to the eyes pick up light signals and alert the rest of the biological clocks. Based on these signals, they work in sync to activate certain hormones in the body that dictate your sleep-wake cycle, metabolism rate, etc. - creating a predictable pattern for your daily life.
Connection Between Hormones, Metabolism, and Circadian Rhythm
Out of all the hormones regulated by the circadian rhythm, melatonin is the key player. It is the central relayer of information about the light-dark cycle to the master clock. When the sun rises, your eyes signal your brain to reduce the production of melatonin and increase cortisol levels to keep you alert. When daylight fades, the melatonin secretion is dialed up to set you up for sleep.
In addition to the light-dark cycle, the master clock keeps track of time by other cues like meal timings, physical activity, etc. Accordingly, the circadian oscillations dictate the digestive system to produce proteins to match eating time and the endocrine system to regulate hormones to suit energy expenditure.
Other hormones that are synced with the circadian rhythm include thyroid hormone, growth hormone, prolactin, etc. The nutrient-sensitive hormones like insulin, leptin, etc. are also modulated by circadian oscillation and their release is somewhat controlled by light-dark cycles, eating time, etc.
Endocannabinoid System and Circadian Rhythm
Several studies have demonstrated that the endocannabinoid system exhibits its own circadian rhythm. The concentration of the endocannabinoid, 2-AG which helps maintain homeostasis in the body, increases three-fold when you wake up in the morning. It continues to hang around at the maximum level between early and mid-afternoon. From late afternoon, the 2-AG concentration begins to go down steadily, takes a nose-dive just before sleep, and hits rock bottom around the middle of the sleeping period - thus completing a circadian cycle.
Driven by the circadian rhythm of the ECS, the stimulation of appetite and food intake increases from morning to mid-afternoon. In response, insulin sensitivity increases in the morning, which enables our body to effectively utilize the glucose from the food intake. Subsequently, insulin sensitivity enters a downward spiral later in the day, leading to reduced glucose tolerance.
The circadian rhythm of the endocannabinoid system is also wired to sleep-deprivation-induced stress and exercise. The concentration of the 2-AG endocannabinoid in the plasma is 80% higher when we are sleep deprived versus normal sleep routine. This coincides with a 25% increase in hunger levels on sleep deprivation. Moreover, physical exercise mobilizes the endocannabinoids resulting in increased circulating concentrations of 2-AG post-exercise.
The significant role of the endogenous cannabinoids in regulating the circadian rhythm of the master clock implies that exogenous cannabinoids too would have a similar impact. Let’s take a look.
How CBD Impacts Our Circadian Rhythm
Sometimes our lifestyle needs and body clock timings do not match. This throws our circadian rhythm out of sync. It could be due to pulling late-nighters, stress, jet lags from crossing time zones, etc. Or, due to medications, injuries, mental health conditions, and other health disorders. When your clock is off, your hormones, digestion, immune system, and most importantly, your sleep cycle take a hit. Without the right signals from your master clock, you are likely to suffer from fragmented sleep, insomnia, and other sleep-related disorders. This is where CBD works its magic.
Owing to CBD’s role in supporting the endocannabinoid system’s pursuit of balance, its administration has been found to have an impact in restoring homeostasis in the sleep-wake cycle. Studies have shown a differential effect of CBD on the circadian sleep rhythm. Low doses of CBD induce a stimulating effect on the rhythm while higher doses cause sedation.
In a study conducted with participants suffering from insomnia, it was observed that administration of 160 mg of CBD daily had the following effects:
- Increased sleep duration
- Reduced instances of waking up during the night
On the other hand, administration of lower doses of CBD caused increased wakefulness. But when it is taken with THC, CBD has a therapeutic impact on sleep in two specific aspects:
- Sleep onset latency, which is the time it takes to fall asleep from lights out
- Short wave sleep, also known as deep sleep when our muscles repair and grow
Naturally, long-term usage of CBD conditions our body clock to an enhanced sleep routine. More specifically, a high dose of CBD combined with a low dose of THC has been found to be effective for improved sleep quality. Apart from dosage, other factors that influence the effect of CBD on the sleep-wake cycle include dose timing, the ratio of cannabinoids, and intake method. For example, sublingual administration of CBD has an optimized outcome since it circumvents the digestive tract and directly hits the bloodstream, generating a quicker reaction.
The reality is, we are all time-bound - as much by the clock on the wall as by our internal timekeeper. In line with the watch that counts down the minutes of the day, our cellular circuits tag team to spur our daily biological processes. From algae to alpaca, every living organism on the planet is governed by it. Fact is, our bodies crave routine. The ebb and flow of daily life that shapes our days is the doing of our body clock. It has a time for everything - a time to eat, a time to be active, and a time to rest. That’s what keeps us going. Turns out, time is all we have.
But for now, the time’s up!