YOUR 2024 BRAIN BRAWN MINI RESOLUTION SLEEP BETTER: WEEK 2

Originally published March 18, 2024

The Circadian Rhythm: Our 24-Hour Cycle of Life

Happy Monday! We hope you tried at least one tip last week and are feeling its positive effects! Need that list of sleep tips again? Here it is:
 

CCP's Curated Sleep Tips

​There are two primary drivers impacting alertness and sleepiness at the right times of day. One is sleep pressure (to be addressed next week) and the other is the Circadian Rhythm.
 
In 2017, the Nobel Prize in medicine was awarded to three scientists for their work on the circadian rhythm (CR). The circadian rhythm is the 24-hour cycle that drives the physiology of being alive. It is typically generated internally but can be modulated by external cues, such as sunlight and temperature. The hypothalamus in the brain is responsible for synchronizing the circadian rhythm. The Nobel Prize Committee’s announcement summarizes the importance of the circadian rhythm to our health and well-being:
 
“With exquisite precision, our inner clock adapts our physiology to the dramatically different phases of the day. The clock regulates circadian rhythmical functions such as behavior, hormone levels, sleep, body temperature and metabolism. Our well-being is affected when there is a temporary mismatch between our external environment and this internal biological clock. For example, when we travel across several time zones and experience 'jet lag.' There are also indications that chronic misalignment between our lifestyle and the rhythm dictated by our inner timekeeper is associated with increased risk for various diseases.”
 
For modern humans, this circadian rhythm misalignment between lifestyle and rhythm is driven by our exposure to the wrong amounts and types of light, at the wrong times of day.
 
The circadian rhythm is one of the many human primitive physiological systems, the stress response being another, that has not adapted to modern living. Cavemen and women rose with the dawn and slept with the sunset. Their days were spent outside and any light exposure at night was fireside. It is specifically the exposure to the blue spectrum of bright daylight in the AM and midday which drives wakefulness through cortisol secretion, and it is falling darkness that stimulates the release of melatonin, the sleep hormone.  Our bodies still require this type and timing of light exposure to function optimally. However, now we rise before the sun, spend most of our days indoors, and go to sleep long after the sun has set with long hours of exposure to blue light from our electronics throughout the day and well into the evening.
 
How can we balance modern living with our primitive physiology? The best way to reset our circadian rhythm is a week of camping under the stars, but we realize this isn’t exactly practical for our purposes here. So, let’s revisit those “Right Light at the Right Time” tips from Week 1, which relate specifically to the circadian rhythm.

Right Light at the Right  Time

Expose yourself to daylight at least twice a day.

Start with first-day sun exposure. It is ideal to nab a 10–15-minute walk outside once the sun is up. If you don’t have the time or if the weather isn’t conducive to outdoor activities, then try standing in front of a window and looking outdoors for a few minutes for a meaningful impact on the hypothalamus. Be sure not to look directly into the sun!

Light is measured in lux units. The approximate lux of the midday sun is 100,000 units and the lux of a typical office is 100-2,000 units—quite a difference! Walking outside for 10-15 minutes after lunch will not only trick the hypothalamus, but it will also have the added benefit of controlling post-prandial blood glucose and provide you with a mental health break. This bio-hack is so powerful we will repeat it often throughout the year!

If getting outside during peak blue daylight hours is not possible, light therapy is an option. Try Googling "Light Therapy Options" to research an indoor light option that can simulate daylight. Curious to know the lux units in your office or home? Google “Lux Meter App Free” and see what is suitable for your device.


Minimize your evening blue light exposure.

All exposure to light after the sun sets affects the hypothalamus and melatonin production (the sleep hormone), and it is the blue light of our electronics that is especially harmful. Sunlight has strong blue light in its spectrum and is strongest from early AM to midday, primitively intended to produce the greatest amount of wakefulness in humans for productivity and safety. Unfortunately, for the purpose of energy conservation, in 1992 our electronics switched from a green light spectrum to a blue light spectrum. Thus, we are kept alert however long we spend on our phones/devices—and melatonin release is delayed and diminished. 

Eliminating our devices is not a practical solution, but there are options for minimizing the impact they have:

Try Googling your specific device to see if you have factory settings installed that allow you to adjust the display spectrum from cool blues to warmer reds. If not, consider searching your app store “Blue Light Filters” for your specific device selections.

Since blue light is in virtually every device as well as in our TVs and artificial lighting, it may be more effective to purchase a pair of amber glasses to wear after the sun sets.

Your third option (and our favorite) is to simply shut it all down an hour before bedtime. Dim the lights, read instead of watching TV and recharge your devices in another room.

​Fun fact!
​Newborns do not have a circadian rhythm. It takes the first 2-3 months of life to entrain the circadian rhythm.
 
We’ll see you next week for a deep dive into increasing sleep pressure.

GLOSSARY OF SLEEP-RELATED TERMS​

​Circadian Rhythm. The 24-hour life cycle of an organism. It is most affected by lightness and darkness and impacts physical, mental and behavioral changes within the organism.
 
Sleep Pressure. The pressure to sleep. It is lowest in the morning upon rising and builds throughout the day to be highest at night.
 
Adenosine. A neurotransmitter that promotes sleep pressure. High amounts of adenosine promote sleep pressure.
 
Sleep Efficiency. The ratio between time spent sleeping vs. time spent in bed. Sleep efficiency of 85% or greater is considered ideal.
 
Sleep Latency. The time it takes a person to fall asleep. Less than 20 minutes is ideal.
 
Sleep Architecture. The basic pattern of normal sleep, divided into REM and non-REM sleep.
 
Glymphatic System. The waste clearance system for the central nervous system. It is most active at night during sleep.
 
Sleep Debt. The difference between the amount of sleep needed and the amount of sleep achieved.

​Use the calendar to log your time in bed. If you have a sleep tracker, log actual hours slept. Note that the benefits of each resolution build upon the others, and the habits we develop are meant to stay with us well beyond the month the resolution is held. We will continue to log meals without sugar alongside our sleep progress.

Feel free to email your Motivated Mondays Coach Michele at [email protected] with your individual questions.

TRACK YOUR PROGRESS: YOUR MINI RESOLUTION TO SLEEP BETTER

Log how many hours you've slept each day, and record which sleep tip you followed from the above link. Click to view and download the log.