Circadian Rhythm Explained with Dr. Catherine Darley
85% of us use artificial light at night. This might not sound surprising or strange, but it does create problems for us and our circadian rhythm.
Our biological clocks, governed by circadian rhythms, are intricately linked to light exposure. When artificial light disrupts this natural cycle, it interferes with the production of melatonin, among other things. As a result, many of us find ourselves tossing and turning, unable to achieve the restorative sleep we need.
On one of the latest episodes of the Sleep Like a Boss podcast I was joined by Dr. Catherine Darley who was kind enough to share her insights on circadian rhythm and as well as some practical strategies to reclaim a harmonious sleep-wake cycle. Dr. Catherine Darley is an expert in natural sleep medicine. Having treated patients for over 20 years, she teaches the sleep skills people need to thrive through her online courses.
How Does Our Body Know What Time It Is?
Healthy circadian rhythm is crucial for quality sleep. Dr. Catherine Darley emphasizes that this internal clock dictates our sleep-wake cycles, impacting not only our rest but also our overall vitality throughout the day. Our circadian rhythm, as Dr. Darley explains, is akin to the orchestra conductor of our bodily functions, orchestrating a symphony of activity that follows a 24-hour pattern. This rhythm isn't confined to a singular aspect of our physiology; rather, it permeates every cell in our body, influencing functions ranging from digestion to hormone secretion.
Consider our digestive system, for instance, which is primed to be most active during the day. Regular meal times align with this rhythm, allowing for optimal digestion. However, disruptions to our sleep schedule, such as staying up late or waking up early for travel, can throw this rhythm off balance, leading to discomfort and inefficiency in digestion.
But how does our body know what time it is? Our circadian system originates in the brain and extends its influence throughout our tissues and cells. This system is finely attuned to external cues, particularly light and darkness, which serve as signals to synchronize our internal clock. Exposure to natural light, especially in the morning hours, triggers wakefulness and sets the stage for a productive day ahead. Conversely, the absence of light signals the onset of evening and prompts the release of melatonin, the hormone of darkness, which prepares our body for rest.
Yet, in today's modern world, where artificial light is ubiquitous, our circadian rhythm faces constant disruption. Dr. Darley highlights that approximately 85% of people worldwide are exposed to artificial light at night, impeding the natural rise of melatonin before bedtime. Without this crucial signal, our bodies struggle to transition into a state of rest, leading to prolonged periods of wakefulness and difficulty falling asleep.
Circadian Rhythm and Adolescence
As we get older, our circadian rhythm undergoes certain changes.
Adolescence marks a crucial period of development where individuals experience a shift in their circadian rhythm, transitioning from childhood to adulthood. Dr. Darley introduces the concept of chronotype, which refers to whether an individual is a morning person, night owl, or somewhere in between. Adolescents, particularly at the onset of puberty, tend to exhibit a preference for staying up later and waking up later, mirroring the traits of night owls.
This shift in chronotype is not merely a matter of personal preference; rather, it is deeply rooted in biological changes occurring during adolescence. Dr. Darley emphasizes that teenagers should not be blamed for their nocturnal tendencies; rather, it is a natural aspect of their development. Despite this, societal norms, such as early school start times, often clash with teenagers' biological clocks, leading to chronic sleep deprivation among adolescents.
Dr. Darley highlights the detrimental effects of sleep deprivation on teenagers' academic performance, social interactions, and overall well-being. Research indicates that a staggering 90% of high school seniors are sleep deprived, underscoring the urgency of addressing this issue.
In addition to adjusting school schedules, Dr. Darley suggests practical interventions to support teenagers' sleep hygiene. She recommends the use of blue-blocking glasses, which have been shown to shift sleep patterns earlier and increase total sleep time in adolescents. Moreover, implementing blue light filters on electronic devices can help reduce exposure to stimulating light, promoting relaxation before bedtime.
But at the same time, Dr. Darley emphasizes the importance of adequate light exposure during the day. Adolescents, like adults, require sufficient exposure to natural light to regulate their circadian rhythm effectively. Dr. Darley advises incorporating regular breaks for outdoor activities to ensure optimal light exposure during daylight hours.
“Research indicates that a staggering 90% of high school seniors are sleep deprived.”
Circadian Rhythm and Shift Workers
Shift workers navigate a unique set of challenges in maintaining a healthy circadian rhythm due to the irregularity of their work schedules. One of the primary difficulties faced by shift workers is the abrupt transition between sleeping during the day and at night, particularly when trying to align their sleep patterns with their work shifts. Dr. Darley explains that the body's internal clock cannot adapt rapidly to such drastic changes, with the general rule being a maximum shift of 1 hour per day.
To address this issue, Dr. Darley emphasizes the importance of creating a consistent block of sleep, spanning at least four hours, regardless of whether it is a workday or not. For example, a shift worker returning home at 8 a.m. may opt to sleep from 8 a.m. to 12 p.m. on workdays and adjust their sleep schedule accordingly on days off. This approach allows for gradual adaptation of the body's circadian rhythm, facilitating restorative sleep and improved alertness during work hours.
Furthermore, Dr. Darley underscores the value of seeking guidance from behavioral sleep specialists to tailor interventions to individual needs effectively. These specialists can provide personalized recommendations on optimizing sleep hygiene, including the timing of light exposure and melatonin supplementation.
Circadian Rhythm and Aging
As we age, our circadian rhythm undergoes transformations, presenting new challenges in maintaining quality sleep. One significant aspect highlighted by Dr. Darley is the prevalence of sleep disorders among older adults, particularly post-menopausal women. She emphasizes the importance of recognizing and addressing sleep disorders effectively, as many of us may be unaware of underlying conditions contributing to poor sleep quality.
Among the sleep disorders of concern in aging individuals, obstructive sleep apnea and restless leg syndrome stand out due to their increased prevalence and potential health implications. Dr. Darley explains the mechanisms underlying these conditions, shedding light on the role of hormonal changes, such as the decline in estrogen post-menopause, in predisposing individuals to sleep-related breathing disturbances and sensory-motor disruptions.
Do we need less sleep as we grow older? Research suggests that older adults likely require the same amount of sleep as during midlife. However, achieving optimal sleep may become challenging due to age-related changes in the circadian system, characterized by a reduced robustness of circadian rhythm. So Dr. Darley advocates for maintaining consistency in daily routines, such as meal times and exercise schedules, to support circadian health and enhance sleep quality.
“Do we need less sleep as we grow older? Research suggests that older adults likely require the same amount of sleep as during midlife.”
Strategies for Improving Circadian Health
When it comes to improving your circadian health dr. Darley outlines some practical steps to that may help improve your sleep quality:
Consistent Wake-Up Times: maintaining consistent wake-up times seven days a week. By adhering to a regular wake-up schedule within a 30-minute window, you can reinforce your circadian rhythm and promote stability in your sleep-wake cycle.
Exposure to Bright Light: exposure to bright light within the first two hours of waking is a crucial component of circadian health. Dr. Darley recommends incorporating outdoor light breaks every two hours throughout the day to reinforce the body's natural circadian rhythm and enhance alertness during waking hours.
Regular Meal Schedules: maintain distinct meal times, avoiding continuous snacking, and ensuring consistency in meal schedules across all seven days of the week. This practice helps synchronize the body's internal clock and optimize metabolic processes, contributing to overall circadian health.
Mindful Bedtime Routines: adopting mindful bedtime routines to prepare the mind and body for restful sleep.Dr. Darley recommends implementing relaxation techniques, such as journaling or meditation, to proactively process the events of the day and alleviate racing thoughts before bedtime. Establishing boundaries and reframing bedtime as a dedicated period for rest and rejuvenation can help you transition into a restful sleep state more effectively.
If you want to learn more about Dr. Darley and her work, make sure you visit her website and connect with her on Instagram and YouTube. Dr. Darley was also kind enough to leave us with a downloadable guide to help you assess your symptoms and design personalized strategies for optimal rest.
