Harnessing Natural Rhythms: The Power of Intermittent Fasting and Morning Sunlight for Recovery

Traditional recovery strategies often focus on passive solutions such as including off days in a regular workout regimen, making time for rest in a busy schedule, and improving sleep habits. While these are all beneficial strategies for giving the body time to recover, they aren’t the only options for promoting overall health and encouraging natural healing processes.

Incorporating holistic approaches to recovery into your wellness efforts can have a positive impact on performance. This can be as simple as adjusting the timing of your meals or increasing light exposure to help set you up for success in unlocking performance goals – and supporting recovery along the way.

WHOOP research investigated the relationship between intermittent fasting, morning sunlight, sleep consistency, and HRV CV in order to better understand the relationship between these behavioral interventions and recovery. By tracking your habits, WHOOP can help you understand your functional patterns, and assess the adjustments your body might benefit from most for optimal health, fitness, and performance.

Exploring the Role of Circadian Behaviors

Circadian rhythm is often referred to as the body’s biological clock. It plays a regulatory role in a variety of physiological processes and behaviors. One of the most commonly cited examples of circadian rhythm in action is the sleep-wake cycle.

Based on environmental cues like light and dark, as well as internal factors including hormone production, metabolic activity, and shifting body temperature, the body goes through regular periods of alertness and sleepiness. Certain lifestyle interventions can help ensure the long-term consistency of the body’s circadian rhythm, promoting optimal performance and recovery efforts. 

What is HRV CV?

HRV or heart rate variability is an important physiological metric that measures the variance in time between heartbeats. HRV is considered to be an indicator of how balanced the two branches of the autonomic nervous system are, and how prepared the body is to respond to cues and perform. 

HRV CV stands for heart rate variability coefficient of variance. This metric is a measure of long-term variability of HRV. With this metric, it’s possible to monitor trends in HRV measures and fluctuations from day to day and over an extended period of time. When there are more fluctuations in HRV data, an individual has a higher HRV CV. Higher HRV CV scores are associated with increased physiological stress and maladaptation to the current training load. 

A high HRV CV can indicate that the body is having difficulty adapting to stress and keeping up with daily lifestyle and fitness demands. Consistently high HRV CV readings suggest that adjustments need to be made to facilitate proper recovery and support overall wellbeing, such as reducing the training load, implementing stress management tactics, and prioritizing rest. Tracking HRV CV and viewing daily fluctuations in HRV readings can provide valuable insight into how new training techniques and recovery efforts are affecting the body, and inform future adjustments.

The Importance of Sleep Consistency

Significant research has been done on the importance of sleep consistency, and findings even suggest that consistency may be more important than duration. Maintaining consistent sleep and wake times may be more beneficial to health and recovery than efforts to increase sleep duration without prioritizing consistency. Increasing total sleep duration is most effective when adopted alongside regular sleep and wake times. 

Consistency goes hand-in-hand with natural circadian processes that operate on a 24 hour cycle. It’s no surprise that sleep consistency is often touted as a beneficial strategy for keeping the body’s circadian rhythm operating smoothly. Sleep consistency can be even more effective at keeping the body’s internal clock on track when paired with additional behavioral interventions, such as optimized eating habits and increased daily light exposure. The most effective interventions are those that align with the body’s natural rhythms and support the cyclical nature of essential physiological processes.

Unlocking the Potential of Intermittent Fasting and Morning Sunlight

Two behavioral interventions that have the potential to enhance recovery are intermittent fasting and morning sunlight exposure. Intermittent fasting involves following a predetermined meal schedule that is held constant on a daily basis. Meals are restricted to fall within certain windows of time, while the rest of the time is spent fasting. One popular strategy is to follow the 16/8 rule, in which food can be consumed during a specified eight hour period each day while the other 16 hours are considered fasting time.

There is also a variation of intermittent fasting specifically linked to circadian rhythm referred to as circadian rhythm fasting. The aim of this practice is to align eating habits with the waking daylight hours and the body’s rest and digestive processes with the less active nighttime hours. Experts theorize that regular, cyclical behavioral interventions support overall circadian function and optimal functioning of the body as a whole. Research has found that intermittent fasting is associated with beneficial changes to the gut microbiome that support optimal circadian rhythm function. 

Another lifestyle strategy that’s growing in popularity is prioritizing morning sunlight exposure. Light is an important external cue for circadian rhythm, so it’s no wonder that soaking up early morning rays can have a beneficial impact on physiological function. Early morning light is considered to stimulate the reset of the body’s daily internal clock and increase alertness to prepare for the day, while darkness triggers tiredness to facilitate nightly sleep.

Getting outside in the morning can help promote the typical sleep/wake cycle and kickstart processes that contribute to elevating alertness and preparing for the day ahead. It also helps maintain the optimal balance between daytime wakefulness and overnight rest, allowing for recovery.

Both morning sunlight exposure and intermittent fasting are accessible lifestyle interventions that can be easily integrated into a healthy routine. No special equipment is needed to reap the benefits of these behavioral interventions. Making the most of these strategies is as simple as making slight adjustments to your daily meal schedule and time spent outside. Once implemented, these strategies support optimal circadian function and can improve sleep consistency and enhance HRV CV, thus promoting better recovery.

Reflecting on the Data

One of the most important takeaways is that intermittent fasting and morning sunlight were both found to improve sleep consistency. According to WHOOP data, practicing intermittent fasting improves sleep consistency by 2.415% and viewing morning sunlight improves it by 2.563% compared to not practicing these interventions. 

In addition, WHOOP research found that intermittent fasting and morning sunlight both improve sleep consistency which in turn improves HRV CV. These results suggest that intermittent fasting and morning sunlight exposure have a beneficial impact on HRV CV through their impact on sleep consistency. 

Improvements in HRV CV indicate that the body is responding well to training efforts, is managing daily stress well, and is recovering optimally. These findings from WHOOP research indicate that intermittent fasting and morning sunlight both improve recovery. Both behavioral interventions positively impact recovery indirectly by improving sleep consistency, while intermittent fasting alone also directly affects recovery itself. Even if you encounter challenges in improving your sleep consistency, adopting intermittent fasting can directly improve your recovery. 

The Path Forward

Explore adding intermittent fasting and morning sunlight exposure to your daily routine to see how they impact your recovery. These behavioral interventions are examples of how taking a holistic approach to recovery can support the body’s natural circadian rhythm and ensure that key physiological processes follow their typical 24 hour cycles without any disruptions. Here are a few simple tips for getting started with these behaviors:

Intermittent Fasting

• Schedule meals between the daytime hours of 7 a.m. and 7 p.m.
• Plan to fast between 7 p.m. and 7 a.m. each night
• Eat larger meals earlier in the day

Morning Sunlight Exposure

• Optimal sunlight exposure time is within one hour of waking up in the morning
• Plan to spend 30-45 minutes in the sun each morning
• Venture outside for direct exposure instead of sitting by a window
• Wear sunblock but avoid sunglasses

Track Circadian Behaviors with WHOOP

Aligning your daily activities with your internal clock when possible can help strengthen overall circadian rhythm and support natural biological functions. Circadian behaviors like intermittent fasting and morning sunlight exposure are just two examples of interventions that can positively influence recovery and circadian function.

With a little extra planning, it’s easy to harness the power of intermittent fasting and morning sunlight to promote a balanced sleep-wake cycle, a consistent circadian rhythm, and improved overall well-being. With the WHOOP Journal, you can track your daily habits — like fasting or heading outside each morning — and monitor changes in key physiological metrics like HRV CV, sleep consistency, and recovery. 

Track your circadian behaviors and get unparalleled insight into your overall health with WHOOP.