Circadian Rhythm
4 tools to leverage yours to promote health and vitality!
I’ve tossed around the phrase “circadian rhythm” frequently on HIB without much more than a surface-level explanation. Hindsight is 20/20 but this topic is so important that it should’ve been included alongside my introductory posts on nutrition and exercise.
Nevertheless, this conversation comes at an ideal time especially for those who sensed they were slow-going last week – particularly the first couple of days. You can likely attribute these feelings to your circadian rhythm being off kilter because of the Spring forward time change.
In fact, the switch to daylight savings time coincides with more than a 5% increase in fatal car accidents caused by impaired reaction times and judgement capabilities.
On the subject of impaired circadian rhythms, physicians working extended hours (often deep into the night) are much more likely to make serious medical errors than those who don’t.
Needless to say, our circadian rhythm is critical to our health… so what is it exactly?
A circadian rhythm is the set of physical, mental, and behavioral changes experienced by an organism over a 24-hour time period – tuned to the daily cycles of day and night.
It contributes to the feeling of hunger, our ability to doze off in the evening, the timing of hormone release, and much more.
Yet not everyone has an optimized circadian rhythm and today you’ll learn multiple strategies to upgrade yours.
It’s important to stage this conversation by bringing to your attention the fact that many of the most distinguished researchers and medical professionals believe a significant number of medical ailments can be attributed partially to an aberrant circadian rhythm.
Study after study demonstrates that the deterioration of one’s circadian rhythm is heavily associated with neurodegenerative disease, cancer, depression, and sleep disorders.
Quick Biology Lesson
I’ll hold back on most of the details but it’s always nice to have a fundamental understanding of how your body works rather than jumping straight to advice.
If you couldn’t care less, jump to the next header.
We have a paired structure in our brain called the Suprachiasmatic Nucleus or SCN for short. The SCN is considered the circadian pacemaker (i.e. biological clock) that controls our daily rhythm. Many different brain structures communicate with the SCN which then transmits signals out to other systems in our body.
I’ll discuss one of the major inputs and one of the major outputs in this system which will paint the picture.
First up, our eyes are a critical input to the SCN. Light waves enter our eyes and are transmitted to the SCN to signal the time of day. The SCN takes this signal in, sets up our daily rhythm (hormone release, mood, etc.), and “starts the clock” on when it will perform a major output task.
The output task being the relay of information to our pineal gland for melatonin release – a hormone which is crucial to our ability to fall and stay asleep through the night.
Of course, there’s much more nuance to it but understanding this makes the forthcoming discussion much more digestible.
Anything that influences our circadian rhythm is coined a zeitgeber – literally defined as a “time clue”. Importantly, it’s these “time clues” we have control over and can develop tools around to get our circadian rhythms dialed in.
Let’s turn our attention to four significant zeitgebers (i.e., time clues) and associated strategies to leverage each of them.
Light/Dark
As already alluded to, light has the most influential impact on our circadian rhythm which makes it front and center in this conversation. When we take in light through our eyes, our internal clock is set in motion. This activation promotes feelings of alertness and vitality in the daytime while also allowing us to fall into a deep snooze at night.
This is the exact reason why morning light exposure has become one of the most frequently promoted health habits in the past few years – without exaggeration, it’s fundamental to our health and well-being.
If you take nothing else from this conversation, strive to get outside for 5-20 minutes of morning light exposure (without sunglasses & not through a window) on most days of the week.
It's imperative to do the opposite in the evening – keep light exposure to a minimum.
Right around sunset, start to reduce your exposure to bright lights (including cell phone light!). Interestingly, there’s been some research regarding the value of actually watching the sun set as another circadian rhythm promoter. The details are less important, but if you needed an excuse to get off the couch, there it is. Go catch a beautiful Midwest sunset!
Big Movers:
(1) Get outside and view morning sunlight on most days of the week.
(2) Keep lights in your household to a minimum after sunset.
Food Intake
Meal timing also plays a key role in setting up your daily circadian cycle. Surprising to some, this starts with the first meal of the day… breakfast.
When we take in food, information is sent to our brain and body relaying we need to be awake and alert. This may seem counterintuitive to those 4-hour Thanksgiving nap takers but there are other things at play in that unique circumstance… including how many adult beverages you had the evening prior.
I digress.
Starting your day with a nutritious, high-protein breakfast is a key component of a proper functioning circadian rhythm. If you’re an intermittent faster, that’s completely reasonable… however, I’d recommend doing most of the other items on this list.
It’s also critical to maintain a hard cutoff on food intake in the evening starting around 3 hours before you intend to hit the hay. This gives time for digestion and allocation of energy to your GI tract prior to the emphasis shifting solely to rest and rejuvenation.
With all of this, maintaining a consistent meal schedule is fundamental. Our brains thrive on predictability, especially when it comes to when we will be taking in energy to fuel our bodies as it sends yet another signal to our internal timekeeper as to what time of day it is.
Big Movers:
(1) Eat on a normal, regimented schedule from ~8am-7pm.
(2) Cut off food intake starting ~3 hours before bed and do NOT “midnight snack”.
Physical Activity
If you thought you could come here without some sort of discussion on physical activity, well, ain’t gonna happen.
As discussed on my recent post regarding exercise and mental health, activity plays a key role in promoting a restful night of sleep… and this is in part due to the influence it has on our circadian rhythm.
However, there’s some nuance to this.
Like light exposure, front loading your day with physical activity may have the most profound impact. The combined effect of light and physical activity is the exact reason Dr. Andrew Huberman put out a social media post last week encouraging people to get outside and exercise whilst facing the sun to promote shifting one’s circadian rhythm to the new clock.
This is NOT to say that afternoon and evening exercise don’t have a positive effect on circadian rhythm… the research just isn’t as clear.
Some studies do show that high-intensity exercise within a couple of hours prior to bed may actually delay our circadian rhythm and make it harder to fall asleep which is something to be cautious of.
Nonetheless, using the excuse to not exercise because you can’t squeeze it into the morning is absolutely not defensible. The benefits of exercise at any time of day 110% outweigh the costs of being inactive.
Big Movers:
(1) Prioritize daily exercise with more intense activity earlier in the day… if possible.
(2) Avoid vigorous activity starting ~2-3 hours prior to the time you plan to fall asleep.
Temperature
For those of us who relish tundra-like temperatures during the evening, this one will strike a chord.
Our core body temperature is aligned with the circadian cycle which shouldn’t come as a surprise. While alert and active, our body temperatures are relatively high and then wane toward the later part of the evening.
In fact, a drop in our core body temperature is necessary to fall into a deep sleep because of the relationship it has with melatonin production.
There are a couple ways to leverage this knowledge.
As mentioned, our body temperature starts to climb in the morning as we become more active. To promote this elevation, the technique of cold immersion via cold shower or a cold plunge can be applied. This may seem counterintuitive but think of it as putting a cold rag over a thermostat – the thermostat senses this temperature adjustment and begins to heat up. The exact same thing happens within our bodies.
A very similar approach can be employed in the evening to assist in lowering our body temperature. Taking a hot shower or sitting in the sauna warms us up for the short-term, however, our brains adjust by cooling our bodies in a rebound-like manner which supports our ability to get into a deep slumber.
On a similar note, sleeping in a cool environment somewhere between 65-68F leverages the same mechanism for a high-quality snooze.
It is important, however, to ensure your body has enough time to cool itself off after a hot shower or sauna. Thus, doing this right before heading to bed may not be the best approach – try to give yourself an hour or so buffer instead.
Big Movers
(1) Utilize cold and heat exposure in the morning and evening, respectively.
(2) Turn down the thermostat at night!
Other Tips
Maintaining a regular sleep and wake time may even be more important than just getting more sleep. Do your best to stay within ~30 minutes or so of each – this includes weekends! Of course, understanding life will get in the way every so often.
The above information can be used for shifting your internal clock earlier or later when traveling to offset jetlag. For example, if you are heading to the East Coast (Eastern Time) from the Midwest (Central Time), moving light exposure an hour earlier and shifting your meal schedule accordingly a few days prior to travel can be of great benefit.
This conversation is ever-so important for shift workers. Although our bodies are not meant to perform on this schedule, one can “trick” their circadian rhythm to promote sleep and restfulness. An example would be to get artificial bright light upon waking (no matter the time) while maintaining a pitch-black environment during “bedtime” by using an eye shade and/or blackout curtains.
Quote of the week:
“A healthy circadian rhythm is the foundation of health. If you’re not entrained to the light and dark cycles, you're not as resilient as you should be!” – Heather Crimson
Citations:
DISCLAIMER
- This is NOT Medical advice. Consult your medical professional before starting any supplement, diet regimen, or workout program
Such great information here!!