Circadian rhythms — also known as our “biological clock” — were discovered by early 18th century French scientist Jean-Jacques d'Ortous de Mairan who noticed that the leaves of mimosa plants opened during the day and closed at night — even in total darkness. As it turns out, this phenomenon isn’t unique to the plant world. These natural internal processes that regulate the sleep-wake cycle and repeat roughly every 24 hours are also foundational to human health and performance.
As research throughout the last few decades has shown, these rhythms play a key role in brain function and overall physical and mental performance. Alcohol, in turn, throws off our circadian rhythm by interfering with the brain's internal clock, the suprachiasmatic nucleus (SCN), and altering the cycles of hormones such as melatonin and cortisol, which regulate sleep, mood, and brain repair processes.
As you leave alcohol behind, understanding your circadian rhythm will support your well-being while helping you stay on track and reach your goals. Let’s look at two recent studies and see how the findings can help you optimize your biological clock.
Circadian Rhythm: What Does Neuroscience Say?
Advancements in the study of circadian biology have provided profound insights into how our internal clocks influence virtually every aspect of our physiology and health. Recently, a preprint study in the Journal of Neuroscience revealed the details of how hormone production and neural connectivity peaks and dips during different times of day and actually induces temporary changes in brain volume.[1]
This study explored how our body's internal clock affects the structure of the brain throughout the day. Using MRI scans and hormone testing, researchers followed a 26-year-old male over 30 days, taking measurements at 7 A.M. and 8 P.M. to capture daily peaks and troughs of key hormones such as testosterone, estradiol, and cortisol. They found that as these hormone levels dropped from morning to evening, the brain's total volume, gray matter, and cortical thickness also decreased, while cerebrospinal fluid (CSF) and brain ventricle sizes increased. These changes were most noticeable in regions such as the occipital and parietal lobes, which are tied to vision and sensory processing.
All in all, the fluctuations in brain volume show that there’s a natural rhythm to the brain's structure driven by hormone fluctuations — one that reinforces how closely our brain function is tied to hormone-driven daily cycles. As you can imagine, circadian rhythm disruptions can throw off the brain and prevent us from functioning at our best — especially when alcohol is in the picture.
Digging Deeper: Circadian Rhythm Disruptions and Mental Health
We’ve known for a while that circadian rhythm disruptions also affect our mood, leading to higher anxiety, impulsivity, and mood swings. A 2020 Nature study reveals the mechanism behind the way in which these disruptions feed into mental health disorders.[2] The authors show that disruptions to these rhythms caused by factors such as shift work, jet lag, or exposure to artificial light at night, can lead to mood disorders such as depression, anxiety, bipolar disorder, and schizophrenia — all of which can make it more difficult to change our drinking patterns and often co-occur with alcohol misuse.
Once again, the problem comes down to the disruption of hormones regulated by the brain’s master clock: melatonin and cortisol, which signal sleep and wakefulness, respectively. When circadian rhythms are misaligned, the hormonal imbalance that happens as a result has a direct impact on mood regulation. For example, shift workers often experience chronic sleep deprivation and increased risk for depression, while jet lag and social jet lag can lead to misaligned body clocks and affective symptoms.
Moreover, the relationship between circadian disruptions and mental health is bidirectional: mood disorders can disturb circadian rhythms, while circadian misalignment can worsen mood-related symptoms. Experimental studies in rodents support this claim and show that even healthy animals develop depressive-like behaviors when their circadian rhythms are disrupted.
The authors of the study end on an encouraging note by suggesting that targeted interventions — which we’ll discuss in the following section — can help realign circadian rhythms and improve mental health outcomes. The main takeaway is clear: addressing circadian disruptions could be a promising avenue for managing and mitigating mood disorders while making it easier to leave alcohol behind.
Strategies To Sync With Your Circadian Rhythm
Implementing a few strategic practices can help you work in harmony with your circadian rhythm and boost daily performance and overall well-being:
1. Maintain a Regular Sleep Schedule
Stick to consistent sleep and wake times every day (yes, even on weekends) to reinforce your natural circadian rhythm. Keeping your patterns regular helps stabilize your internal clock, leading to better sleep quality and more energy during waking hours. It's not just about the amount of sleep you get — it’s also about the consistency of timing that supports your body's natural processes.
2. Time Your Meals Strategically
Eat larger meals during daylight hours when your metabolism is more active and taper off food intake as evening approaches to align with your body’s slower nighttime metabolism. This practice supports your body’s natural rhythm and can help in weight management. Research indicates that aligning your eating patterns with your circadian rhythm enhances digestion and optimizes nutrient absorption.
3. Increase Exposure to Natural Light
Spend time outdoors in natural light, especially in the morning, to help reset your circadian clock and boost mood and alertness. Morning light exposure helps regulate sleep patterns and can help combat sluggishness.
4. Limit Evening Blue Light Exposure
Reduce exposure to screens and artificial lighting in the evening to help your body prepare for sleep by naturally increasing melatonin production. The blue light emitted by screens disrupts your circadian rhythm by tricking your brain into thinking it's still daytime, thus delaying sleep onset. Consider using apps that filter the blue spectrum or wearing glasses that block blue light after sunset.
5. Incorporate Relaxing Evening Routines
Develop a calming bedtime routine to signal to your body that it's time to wind down. Winding down could mean reading a book, taking a warm bath, or practicing relaxation exercises such as deep breathing or gentle yoga. These relaxing routines support your body's natural progression towards sleep.
6. Set the Right Temperature
Adjust your sleeping environment to a cooler temperature at night. The drop in core body temperature is a signal that helps trigger sleepiness. (Exactly what that temperature is might vary, but will tend to fall in the 65-68 degree range.)
7. Limit Caffeine Intake
Monitor and manage your intake of caffeine, especially in the hours leading up to bedtime (after around 4 pm). Caffeine can significantly disrupt your sleep cycle by delaying the timing of your body clock.
Summing Up
Circadian rhythms are central to our overall function and well-being — and we have the power to control them! By understanding and aligning your routine with these natural patterns, you can optimize your mental and physical performance, enhance your health, and improve your ability to function effectively, coast through cravings, and build momentum in your journey.
