Circadian Misalignment In Night Shift Workers

In the modern world built upon shift-based work schedules, it is important to recognize

how these shifts may disrupt our natural circadian rhythms, affecting our overall health and

wellbeing. Specifically, night shift workers are forced to undergo abrupt changes in sleep timing

and light-dark exposure.

Simulated night-shift experiments and field studies indicated that the human circadian

system is very resistant to adaptation from day to night-oriented schedules. This is seen

specifically in the lack of phase shift and dampening of important hormone rhythms, such as

melatonin and cortisol. To understand how our circadian system is affected we must first

understand the molecular mechanism that makes up the circadian clock. The core lies in the

brain’s suprachiasmatic nucleus, which produces a set of autoregulated feedback loops through

clock genes that are expressed in a 24 hour cycle. From this, the body’s peripheral tissues are

able to generate self-sustained circadian rhythms, known as “peripheral clocks”. These molecular

mechanics allow for a general day-to-day flow of bodily functions and hormones to optimize

digestion and sleep patterns.

For instance, the peak of melatonin, and trough of body temperature and cortisol,

normally occur in the first, middle, and last thirds of the nocturnal sleep period. This allows for

more peaceful and deep sleep. Melatonin production is influenced by light, which is the most

important synchronizer of the central circadian clock in humans. When the SCN receives light,

melatonin hormone production decreases, while cortisol rises. In this same way, our digestive

patterns are influenced by the ebb and flow of our metabolism. The hormone Leptin reduces

appetite and signals the cessation of food intake, while the hormone Ghrelin signals for

food-seeking behaviors in the reverse pattern of Leptin. As seen in the Ayurvedic Clock, we

should eat our largest meal at noon, when our digestive fire is the highest. Our body reflects this

principle through hormones that work in harmony with our body’s metabolic processes to allow

for smooth and productive digestion during the day. In conjunction with highest metabolic rates

during light hours, Leptin and Ghrelin typically work together in a feeding/fasting cycle to

ensure food intake at the most optimal time for our body’s digestive system.

However, when an individual is working night shifts, the nocturnal sleep period is turned

into a wake period that involves the stress of work. This circadian misalignment dampens

hormone rhythms, meaning that the peaks and valleys are not as pronounced and affective. This

results in disrupted coordination of hormones that lead to a higher presence of disease and

disorder in night shift workers. For instance, laboratory circadian medicine studies demonstrate

that night shift work leads to a decrease in Leptin levels and a blunted post-mean suppression of

Ghrelin. This results in a cycle of disrupted hunger cues, high caloric intakes at odd hours,

unhealthy glucose spikes, and overall poor metabolic health. This contributes to higher rates in

diseases like Type 2 Diabetes and Metabolic Syndrome. In terms of the dampened melatonin and

cortisol patterns, we see that the quality of sleep is poor leading to high rates of insomnia and

daytime sleepiness that can persist for years in former night-shift workers. This is seen in

experimental results when comparing night and day-shift nurses. The night-shift nurses had a

scattered and dampened melatonin rhythm in comparison to the clustered and well aligned

hormone rhythms in day-shift nurses. This dip in melatonin is known to be dangerous, as this

hormone is protective against oxidative DNA damage. Therefore, when melatonin production is

suppressed, DNA damage may accumulate faster than it can be repaired, which may contribute

to an increased cancer risk observed among shift workers. 

In addition, taking melatonin or digestive supplements that initially increase the hormones 

needed to regulate biology, over time send messages to the body that suppress their 

production and in the long term, reduce the body's ability to make them, and thereby weaken

and disrupt the system further.

Resources:

Download our Beneficial Daily Routine

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8832572/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5647832/

Circadian Rhythms & the Ayurvedic Clock

 

Background on Circadian Rhythms

The emerging field of circadian medicine shows an intrinsic link between our body’s

biological clocks and the light/dark cycles of nature, as affirmed by Ayurveda. “Circadian

rhythms” refer to the physical, mental, and behavioral changes that flow in cycles within our

body over a 24 hour period. Specifically, a part of the brain called the suprachiasmatic nuclei

(SCN) is synchronized to the 24 hour light/dark cycle. In the absence of light, the pineal gland

produces a hormone called melatonin, which increases our inclination to sleep and acts on its

receptors to aid in the synchronization of circadian rhythms in our body's tissues. This process is

referred to as “dim light melatonin onset” (DLMO), as it allows for an increase in melatonin

synthesis during darkness and slows production during daylight. While it is synced to the

presence of light, our feeding/fasting patterns are the main time cues for clocks in these tissues.

This creates preferred feeding times to fall in line with our metabolic changes throughout the

day. The circadian system prepares our body for daytime feeding with our gastric emptying and

gastrointestinal motility rates peaking during daylight hours.

Disruption of the Circadian System

While circadian rhythms are able to adapt quickly to our individual feeding, sleeping, and

physical activity habits, several of our peripheral tissue clocks (such as the liver clock), are

especially sensitive to the quality and timing of food consumption. This disruption of our natural

rhythms is a growing concern in our society as we are in the age of artificial lighting, jet lag,

night shift work schedules, and constant availability of energy-dense food. Because of this

sensitivity in our body's tissues, the disorganization of circadian rhythms caused by irregular

nutrition patterns is thought to play a part in the development of certain chronic diseases. By

using nutrition as a tool to align our energy intake with peak energy expenditure and metabolic

changes influenced by nature’s light/dark cycles, we can maintain a more healthy circadian

system. This concept is explained more simply using the Ayurvedic Clock, which directly

correlates with scientific research on the body’s circadian rhythms.

The Ayurvedic Clock & Nutrition Patterns

The Ayurvedic Clock recognizes our body’s synchronization with the light-dependent and 

seasonal and daily cycles of nature. The 24-hour Ayurvedic Clock falls in line with our 

optimal sleep/wake cycles,  hormone-release cues, eating habits, and digestion patterns. 

The Ayurvedic Clock can be categorized  into six parts, which includes three cycles that 

occur during the day and three cycles that occur during  the night. Ayurveda’s foundation 

is built upon the three Doshas: Vata, Pitta and Kapha, which combine  the five elements 

(ether or space, air, fire, water and earth) and govern our physical and mental  tendencies. 

Vata is considered the lightest dosha (ether/space and air), Pitta is the hottest dosha 

(fire and water), and Kapha is the densest dosha (water and earth). The day/night cycle is

controlled by these doshas, which guide us on h ow to act according to our body’s natural 

rhythms, as described in circadian medicine.

Day Cycle

KAPHA: 6 am – 10 am

In line with the daylight, Ayurveda suggests starting our mornings with exercise and a light meal

for breakfast.

PITTA: 10am - 2pm

The sun is highest in the sky, which calls for high productivity in light with our increased

metabolic rates and peak digestion. This prepares our bodies to have the largest meal of the day

for lunch.

VATA: 2 pm - 6 pm

Vata represents the time of transition, which is best-accompanied by creativity, deep thinking,

contemplative practices, such as yoga and meditation.

Night Cycle

KAPHA: 6pm - 10pm

Kapha’s heavy qualities dominate, which is used as a signal to wind down, have a light last meal,

and prepare for sleep.

PITTA: 10pm - 2am

Sleep governs this time in order for cleansing of our internal organs to take place.

VATA: 2am - 6am

This marks another period of transition, which makes this time block ideal for spiritual and

contemplative practices.

For more information on Ayurvedic Nutrition Education and Health Coaching, please contact us

for information or an appointment.

Resources:

● Potter, Gregory, et al.“Nutrition and the Circadian System”, National Library of Science
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4930144/

● Maibam, Punyakishore, “Role of the Ayurvedic clock in boosting the immune system”,

● Journal of Ayurvedic and Herbal Medicine, https://www.ayurvedjournal.com/JAHM_202392_08.pdf

● Douillard, John. “Circadian Rhythms 101: Nobel Prize-Winning Research Validates the
   "Ayurvedic Circadian Clock”

● Chaya's Guide Book; Introduction to Ayurveda and Healthy Living, Chaya~Sharon Heller,
Ayurvedic Practitioner, Yoga Therapist, Holistic Health Educator, LMT

August Featured Service: Ayurvedic Nutrition & Digestion ~ Blog #1: Mindful Eating

 

In a busy world with stacked schedules, it is easy to feel as though it is more productive to skip or grab meals on the go. However, changing our perception around eating a meal can have extensive benefits on our mental and physical health, including maintaining or achieving a healthy weight, controlling diabetes, managing depression/anxiety, aiding digestion, and countering disordered eating patterns.

            We often mindlessly eat while watching television, scrolling, driving, or in the middle of work. As we multitask during mealtimes, we often neglect paying attention to our food and before we realize it, the plate is empty. This often leads to overeating, trouble with digestion, and long-term gut health conditions. To counter this habit, “mindful” or “conscious” eating allows us to form a deeper mind-body connection, better understand our satiety levels, and create a better relationship with food. 

The Body’s Digestive Patterns

Our digestion is controlled by the autonomic (involuntary) nervous system. When eating a meal while multitasking with watching a TV drama, for example, you may feel mixed emotions like fear or anger as you eat your food. When this happens, the “fight-or-flight” sympathetic nervous system is triggered. This causes an increase in blood supply to peripheral muscles rather than the digestive organs. As a result, the movement of food through our digestive tract is slowed, causing discomfort and indigestion pains. This delayed digestion also results in skewed hunger cues. Our brain needs at least 20 minutes to register the digested food. Therefore, rushed eating often leads to us feeling hunger very soon after a meal. This often encourages overeating that lead to metabolic conditions, such as diabetes, cardiovascular issues, and obesity.

However, when practicing mindfulness while eating, the “rest-and-digest” parasympathetic system is active. This aids in regulating the involuntary body functions while you are at rest, which include heart rate and digestion. This strategy has been shown to help treat those with binge eating disorders and depression. This is largely due to forming an intrinsic recognition of emotional versus physical hunger through deeper awareness and mindfulness practices. 

Mindful Eating in Ayurveda 

We can create a heightened sense of awareness during meals by bringing more attention to each sensation we feel while eating. This includes the flavors, textures, and the positive energy we may feel after nourishing our bodies. By creating a log of this sensory experience, we are often left feeling more satisfied and grateful for how the food we eat is able to fuel the body. 

The concept of mindful eating has roots in Ayurveda, which places a huge focus on the link between the mind and digestion. According to Ayurvedic practice, we should eat as much as is enough to not feel hungry, rather than eating until full. This means that ideally around ¼ to ⅓ of the stomach should remain empty. A sign that this limit has been reached is the first full burp, which means the stomach is likely three-quarters full and we should stop eating. 

How to Eat Mindfully

To practice mindful eating, we can implement small changes to gain a greater sense of mind-and-body connection, and therefore a better relationship with food. Some changes we can implement include:  

●       Taking a moment to be conscious of why you are eating to avoid emotional/stress eating

●       Being present when grocery shopping to buy nourishing foods, such as seasonal fruits and vegetables

●       Cooking your own food to create a stronger relationship to the source of each ingredient and appreciation for the time and energy you infuse into each meal

●       Favor cooked food with spices over raw foods as it is easier to digest and strengthens metabolism and digestive capacity

●       Avoiding “incompatible foods” that may negatively impact digestion, adversely affecting your constitution resulting in accumulation of ama, or toxins in the body 

●       Making lunch your biggest meal, as this is when the body’s digestion is at its peak

●       Avoiding meals within three hours of bedtime to give the body enough time to fully digest and wind down

●       Examining portion sizes to ensure that we are not eating to much or too little

●       Eating without distractions or multi-tasking to draw more attention to our food and digestion

●       Chewing slowly and taking manageable bites to avoid rushed eating

●       Taking note of the sensory experience of each meal, including taste, aroma, texture, sounds, and aftertastes

●       Eating with gratitude to remind ourselves of the strong value that food has to our physical and mental health

●       Sitting quietly for a few minutes after eating to stay present and fully acknowledge each meal 

August 2024 Featured Service: Ayuvedic Nutrition Program

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Reference:

●       Chaya’s Guidebook: Introduction to Ayurveda & Healthy Living
Free with an Ayurvedic Discovery Consultation with Chaya