THE 'BER MONTHS ARE HERE! BE A RAY OF SUNSHINE
Dr. Krista Coombs, DrAc, IFMCP
September 12, 2025
Most of my early life was spent in Labrador - a beautiful Northern region of Canada! It’s an amazing part of the world to grow up in. I particularly learned to LOVE Winters! I experienced long, cold, ❄️snowy yet bright Winter months there, loving all the Winter sports and quiet lifestyle. My body became very well adapted to the light and cold changes with the seasons, and I really thrived.
But I remember a friend of mine who came to visit me in the middle of a Labrador Winter one year and he genuinely couldn’t stay past a month because his body, adapted to Venezuela, just rebelled so severely! It would likely have taken him years to adapt, I suspect.
🌞There is POWER in sunlight and our bodies can adapt to the variations depending on where you live and how long you live there. Understanding how this applies to you is key to learning to live in sync with the natural cycling of the sun’s rays throughout the seasons.
So, let’s dive into the power of sunlight for your YOUnique body, living where you live right now, as you are entering the 'ber months of Fall - September, October, November and then December for Winter.
I’d like to shed some light (pun intended) on navigating this seasonal change so that you have the opportunity to optimize your energy, stabilize your moods, get more restorative sleep and reduce weight gain. Sound like something you’re interested in? I hope so, because if you choose to practice what I teach you here, you can experience a very different Winter this year and for many years to come.
Winter life for those of us who grow up in the more Northern hemisphere regions like I did, is something our bodies adjust their biology to. The body has to learn to harness the power of sunlight, changing temperatures and changing food availability so that it thrives while surviving.
And, as we ladies age into peri and post menopause, this kind of optimization with connection with Nature can be the difference between a thriving happy time or a quicker decline to frailty.
So, listen up and get to work on what you learn!
Winter is NOT the enemy for our bodies in the Northern hemisphere, though many feel it is.
People pop Vitamin D capsules like they are candy in the Winter months (and often all Summer long too), but this is NOT usually the answer, often not even in part, to remedying declines in immune function, weight regulation, mood and more. That will be a conversation for another blog article, but right now, I’ll help you explore the changes in light in the Northern hemisphere, the impacts on your health, and how to practice being in more alignment with the colder, darker seasons to support the healing of your body.
YOUR BODY SHIFTS IN THE 'BER & WINTER MONTHS
Your biology – your body – EXPECTS the days to get shorter, the temperature to get colder and that some foods will no longer be available where you live.
It is BUILT to adapt your chemistry with the changing of the seasons.
But, modern life literally fights against these natural circannual rhythms by us staying inside our warm, air tight homes and work places all day and night long with little outdoor time, long nights exposed to indoor blue lighting from our tv’s, computers, phones and lamps, and foods shipped to our grocery stores from hotter places on Earth very unlike where we are living! It messes with our biology to our detriment.
In contrast, when you learn to harness the immense influence and power of light, cold, and nutrition the way your body was designed to do, Winter is no longer just a season to endure but becomes a natural season where your body gets to restore, recharge, and reset.
LIGHT CHANGES IN THE 'BER & WINTER MONTHS
As September arrives in the Northern hemisphere, our biology starts to majorly shift.
In terms of the influence of light from the sun, 🌞UVB spectrum light (Ultra Violet B) – the part that helps our skin make Vitamin D from cholesterol – essentially disappears for a number of months!
Now, this is not permission to pop more Vitamin D pills, my friend! Keep reading!
To avoid the stereotypical weight gain, depression and sleep issues, etc we associate with the darker, colder months, as the ‘ber months turn into Winter ones, it largely comes down to understanding how to live seasonally and take advantage of the sun exposure opportunities available where you live.
It’s not all just about Vitamin D production even though D is essential for turning off 1000’s of genes, modulating immune function, building bones and so much more. Sunlight is more than just UVB and Vitamin D production.
🌟I learned the following stats from an amazing colleague, Sarah Kleiner, who specializes in quantum biology and light therapies. Her app, MyCircadianApp, is worth spending time exploring if you find your curiosity piqued about light’s influence on your biology. To get her premium version as a trial, use her code SARAHK.
PAY ATTENTION TO THESE UVB LIGHT STATISTICS ⬇️
I hope you find this just as fascinating as I did upon first learning this information from Sarah! For me, living at around the 50° latitude area in Canada, I learned UVB light is essentially not present for 6+ months of the year! Check out the stats for you below.
Who loses UVB spectrum light?
Around 35° latitude (roughly Los Angeles, NC/TN border, southern Spain, southern Japan) and northward, UVB rays (290–315 nm) become insufficient for vitamin D production in winter
By ~42° latitude (Boston, Rome, Chicago, Beijing), vitamin D production essentially shuts off for 4–5 months
At 50° latitude and higher (London, Berlin, Calgary), you can go 6+ months with no usable UVB
At 60° latitude and higher (Stockholm, Helsinki, Alaska), it can be 7–8 months of no UVB-driven vitamin D synthesis (and no UVA spectrum light for some parts of the year)
Which months are UVB spectrum gone?
30° latitude (Atlanta, Houston, Cairo, Florida): usually maintain vitamin D synthesis year-round, though efficiency is lower in Winter
35°–40° latitude (Denver, Madrid, Tokyo): Vitamin D Winter lasts ~2 – 4 months (Nov – Feb)
40°–45° latitude (New York, Milan, Toronto): Vitamin D Winter lasts ~4 – 5 months (Nov –Mar)
50°–55° latitude (London, Berlin, Calgary, Vancouver): Vitamin D Winter lasts ~5 – 6 months (Oct – Mar)
60° latitude+ (Oslo, Helsinki, Alaska): Vitamin D Winter can last 7 – 8 months (Sept – Apr)
What UVI (Ultra Violet Index) is needed to make Vitamin D in the skin?
A rule often cited is that you need a UVI of ~3 or higher to make vitamin D, but that’s only a general population guideline.
Lighter skin can sometimes make Vitamin D at UVI 2 – 3, since less melanin filters the UVB.
Darker skin usually requires UVI 4 – 5+ and longer exposure, because melanin naturally blocks UVB.
Latitude & solar angle matter: At higher latitudes, even with UVI ~3, the low sun angle in winter means almost no usable UVB reaches the skin. Midday exposure is essential.
Individual biology matters: Age, body composition, and mitochondrial genetics all shift how efficiently you convert sunlight to Vitamin D.
In summary, though a UVI of 3 is a general marker to look for, it may be higher or a little lower for you depending on your skin colour, your ancestry (genetics) and your environment (inside tons or outside often and diet and cholesterol levels). And paying attention to UVB changes where you live can help you adjust your lifestyle to optimize harnessing the power of sunlight throughout the year.
VITAMIN D IS ONLY ONE PIECE OF THE SUNLIGHT PUZZLE
Ok, so the UVB light starts disappearing come the ‘ber months and through Winter which interrupt your body’s potential to make Vitamin D.
But not all is lost! Other wavelengths of light – namely, UVA (Ultra Violet A), near infrared (NIR) and far infrared (FIR) – continue to make it to the Earth’s surface all year long, and they impact your physiology a massive amount too.
Even when the UVB is gone in the darker months, sunlight, with its myriad of spectrums remaining, helps to regulate appetite, stabilize mood, protect mitochondria, and even help conserve the vitamin D you already have!
Sunlight is a full-spectrum therapy.
🌞UVA EXPOSURE
UVA (315- 400 nm) is your hidden friend during the Winter months, because unlike UVB, it’s still abundant across most latitudes.
The eyes are especially sensitive to UVA. Through the retina of each eye, UVA boosts the production of the neurotransmitters, serotonin and dopamine. UVA can help trigger the hunger and satiety hormones too, ghrelin and leptin. This collection of neurotransmitters and hormones help stabilize your mood, appetite, sleep, fat mobilization, and energy. For example, much of the serotonin you make during UVA exposure is also recycled into that night's melatonin which helps you have a quality sleep for regeneration. And listen up ladies, we make more melatonin than men in Winter-time, on average, so this is pretty important.
So, when you experience first morning light, without sunglasses or a window pane in the way, the light is signaling your skin and also your eyes and therefore brain to help stabilize many hormones and keep your biology in sync with the season it’s in!
Therefore, a very powerful and simple daily reset for your brain involves exposure to early morning sunlight, even for just a few minutes, every day of the year!
Keep this stat in mind that morning light while outdoors typically measures between 1000 and 100,000 lux. To put this in perspective, indoor light is only ~100 – 300 lux and studies show you need at least 500 lux in the morning to properly align metabolism, appetite and mood.
Without this morning light signal, your brain will experience the day as “permanent dusk,” which in turn will exacerbate cravings, fatigue, low energy, and increased risk of seasonal depression.
If you use the MyCircadianApp to track lux where you live, ensure you keep lux below 10 for the 3 hours before bedtime to protect your melatonin levels for better sleep.
🌞NIR EXPOSURE
Near infrared (NIR) light uniquely penetrates deep into your tissues, stimulating the production of mitochondrial melatonin.
Unlike the melatonin that rises at night from the pineal gland in your brain, mitochondrial melatonin is made locally inside nearly all of your cells to protect mitochondria from oxidative stress.
During low-UV seasons like Winter, NIR becomes especially important for your health. NIR light strengthens cellular defenses, supports mitochondrial efficiency, and even helps buffer the immune system when Vitamin D levels are lower.
And of important note, NIR is present all year long, even on cloudy days and through snow, making it one of the most reliable forms of light to keep your biology resilient in the darker months.
🌞FIR EXPOSURE
Now, this next part might be very new to you. It’s an incredible concept about a fourth phase of water that forms around protein and membranes in the body. It’s called Exclusion Zone water – or EZ water.
Far infrared (FIR) light plays a unique role in creating EZ water which can then act like a cellular battery, storing energy from the sun and improving the efficiency of cellular biological processes!
And in Winter when UVB-driven Vitamin D production is naturally lower, EZ water can act as an alternative energy reserve to help your cells function optimally until Spring and Summer arrive.
And like NIR light, FIR light penetrates deeply and is available all year long, even on cloudy days and through snow, making both forms of light consistent signals supporting your biology in the darker months.
🥶COLD EXPOSURE
This is a huge topic on its own, but I wanted to give a special nod to it in this blog article as it is a powerful natural biological cue to our bodies in the ‘ber months, through Winter.
Cold exposure will be a natural part of the darker, colder Winter months that help your body adapt to those changing conditions.
Cold stimulates mitochondria to release biophotons which are ultra-weak light emissions from inside cells that can possibly help preserve Vitamin D stores and support cellular communication when parts of sunlight and length of sunlight exposure are scarce.
Think about how super cool this is! When UVB light and therefore, Vitamin D production, drop as the ‘ber months begin, progressive cold steps in to complement this process and acts as a stimulus to strengthen your immunity, build resilience and to stabilize energy. So, getting cold exposure over these months is a simple way to support your health, along with light exposure, especially in the early morning hours.
VITAMIN D DIPS IN WINTER – THIS IS NORMAL
A natural part of your circannual biology is that your Vitamin D levels are actually supposed to dip slightly in the Winter months.
Before Vitamin supplementation was an option, our biology was naturally set up to be in rhythm with the seasonal light show! So, dosing high in Vitamin D with supplements may not necessarily be the answer to your Winter woes.
🌞LIGHT IS THE ANSWER.
So, yes, the Vitamin D dip is natural. But with our modern lives, we accelerate it with gusto! Many of us spend all day inside buildings, under artificial lights that lack UVA, NIR and FIR light, then are blasted with blue light throughout the day and into the night hours, pushing our bodies further and further out of sync with Nature’s intelligent ways.
Our bodies are not built for this onslaught of modernity.
They haven’t adapted to it.
So, if you’d like to experience the ‘ber months into Winter - with the longer dark periods and weaker light periods - and have more stable moods, better hunger cues, less weight gain, and optimal sleep, I’d like you to consider these few things to get your started. To dig deeper, give me a call for some personalized support.
4 THINGS TO GET IN SYNC IN THE DARKER MONTHS
Download Sarah Kleiner’s MyCircadianApp and use her code SARAHK to trial her premium version (I have no financial affiliation). Figure out sunrise, lux and sunset for where you live.
Ensure daily, first morning sunlight exposure outdoors as per the app, without sunglasses on or a window to block you, for about 10-15 minutes.
Track how you feel as you continue doing this simple routine over months.
Spend some time each day outdoors, experiencing the weather as it shifts into Fall and into Winter. Feel the cool air. Go for a walk, or do yardwork, shovel snow once it falls, and even consider ending your warm morning showers with a cold water blast for 30-60 seconds. It REALLY works to help with body resilience by impacting things like dopamine levels and heat shock proteins!
I’d love to hear how you do with the app, tracking and the actions I recommend to get you started supporting your circannual rhythms, starting now in the ‘ber months and over the Winter months. Who knows - you might start loving Fall and Winter like I do as you learn how to be more in sync with the sun and Nature.
It’s still important to know your Vitamin D production over a year in case your body isn't making enough during the higher UVB times or using it up faster than typical or if your cholesterol levels are sub-optimal.
So, if you’d like to learn about your Vitamin D levels, I stock Vitamin D test kits in clinic or we can ship it to you, to check your Vitamin D level in the Fall, to learn how much D you are leaving the high UVB months of Summer with, then supplement over Winter if advised, and recheck levels in the Spring. If we have these bookended D values, you can be knowledgeable about how to dose D through supplementation, if needed, and how much more sun exposure to focus on.
In Functional medicine, we like the Vitamin D level to be between 60 and 80 ng/dL. Yes, it’ll dip in Winter, but I like to see it stay at least around the lower functional range at that time. Best to test, not guess!
Hugs,
Dr. Krista
DrAc, IFMCP
CHECK OUT HOW TO WORK 1:1 WITH ME (Acupuncture, Consultations)