Every fall, the pattern repeats. As daylight fades, you watch your child, or maybe yourself, begin that familiar slide. Energy drops. Emotional instability shows up. Motivation vanishes.
Experts call it Seasonal Affective Disorder (SAD). They explain how reduced sunlight decreases serotonin levels and disrupts your circadian rhythm. They recommend light therapy, maybe antidepressants, and tell you it’s your brain chemistry responding to shorter days.
They’re right, to a point.
But here’s what they can’t explain: Why do some people handle seasonal transitions effortlessly while others struggle significantly? Why do children with Autism, ADHD, or sensory issues predictably worsen each winter? Why does one sibling thrive year-round while another battles the same seasonal decline?
The answer isn’t just about what happens during seasonal depression. It’s about why certain nervous systems lack the capacity to adapt to environmental changes.
How Seasonal Changes Affect Brain Chemistry and Mood
Before understanding why some nervous systems struggle more than others, let’s establish what actually happens during seasonal depression. The conventional medical understanding provides important context, but it just doesn’t tell the complete story. As I often like to say, it’s accurate but incomplete.
The Role of Light in Regulating Neurotransmitters
Sunlight does more than help us see. It plays a direct role in nervous system regulation and balancing the brain chemistry that affects mood, energy, and sleep.
When light enters your eyes, it triggers neurological responses. Research shows that reduced sunlight during fall and winter decreases serotonin production—the neurotransmitter responsible for mood regulation and well-being. Simultaneously, the brain increases melatonin levels, leading to sleepiness and lethargy.
This shift creates the physiological basis for SAD signs: persistent low mood, decreased energy, increased sleep needs, and carbohydrate cravings. Your circadian rhythm, the internal clock that regulates sleep-wake cycles, relies heavily on exposure to light. When daylight shrinks from 15 hours in summer to 9 hours in winter, that timing system struggles.
Vitamin D deficiency compounds these effects. During winter months, especially in northern latitudes, vitamin D levels drop significantly. Low vitamin D correlates with increased depression signs and impaired immune function.
These are measurable changes in brain chemistry that create the physical foundation for seasonal depression.
Brain Regions Involved in Seasonal Depression
These neurotransmitter changes affect specific brain regions responsible for mood regulation.
The dorsal raphe nucleus houses approximately half of the serotonin-producing cells. When light exposure decreases, this region shows reduced activity. People with SAD show different serotonin transporter patterns in winter—their brains increase serotonin uptake away from mood regulation.
The prefrontal cortex and limbic system—areas involved in emotional processing—show altered function during seasonal depression. These regions don’t communicate as effectively when serotonin levels drop, which explains cognitive symptoms such as difficulty concentrating, reduced motivation, and decision-making problems.
Research has even identified changes in retinal sensitivity. People with SAD show decreased rod sensitivity during winter, meaning they’re literally less able to detect available light.
This research explains what happens and the specific mechanisms that shift as daylight decreases.
But it doesn’t explain why these changes affect some people minimally while overwhelming others. That requires looking beyond brain chemistry to nervous system regulation and resilience.
Put simply, we need to ask the deeper question – what if the nervous system was already dysregulated and out of balance going into fall and winter? If that is the case for some kids and parents, they are much more likely to struggle significantly when all these other factors come into play.
Why Some Nervous Systems Can’t Adapt to Seasonal Transitions
Here’s what conventional understanding misses: Not everyone who experiences reduced sunlight develops Seasonal Affective Disorder.
Two people can live in the same city, get the same amount of daylight, and one thrives while the other can barely function. The difference isn’t about attitude. It’s about nervous system function, regulation, and something called reserve capacity (which can actually be measured using HRV testing).
The Nervous System Resilience Factor
Your Autonomic Nervous System operates like a car with two pedals. The Sympathetic Nervous System acts as the gas pedal, activating stress responses—increasing heart rate, mobilizing energy. The Parasympathetic Nervous System acts as the brake pedal, promoting rest, digestion, and recovery.
A healthy nervous system shifts smoothly between these states. You need the gas pedal when challenges arise. You need the brake pedal to rest, digest, sleep, and maintain emotional balance.
The vagus nerve serves as the major communication pathway between your brain and organs, regulating digestion, heart rate, immune response, and stress adaptation. When this function operates optimally, your nervous system assesses stress accurately and responds appropriately.
But some nervous systems get stuck. The gas pedal stays pressed—sympathetic dominance—even when no threat exists. The brake pedal doesn’t engage, so true recovery never happens. This isn’t a choice. It’s nervous system dysregulation.
Think of a smartphone battery. A healthy battery handles regular use plus high-demand activities. A damaged battery drains quickly from basics alone.
Some nervous systems handle daily life plus seasonal transitions. Others are already operating at maximum capacity. When seasonal changes arrive, there’s nothing left in reserve.
We can now measure the health of our body’s battery using INSiGHT Scanning Technology, especially HRV (Heart Rate Variability). Going into the fall and winter, knowing the true status and functionality of your body’s battery and nervous system is essential.
Seasonal Transitions as Additional Neurological Work
Seasonal changes require real adaptation work from your nervous system.
Your body must adjust circadian timing to new light patterns. It must maintain neurotransmitter production despite reduced sunlight. It must regulate temperature in colder weather. It must support immune function during cold and flu season. Each adaptation requires additional neurological resources and adds to the list of “work” that must be done in this season.
For a nervous system with healthy capacity, this happens automatically. You notice shorter days but don’t feel overwhelmed. Your body adapts quickly, efficiently, and easily.
For an overwhelmed nervous system, seasonal transitions become the breaking point. We’re asking our systems to do more work during seasonal transitions. For a system already operating at its limit, this is the tipping point at which many people, even children, fall into what we call neurological exhaustion.
This explains patterns you’ve probably noticed. Children with Autism, ADHD, or Sensory Processing Disorder often worsen each fall and winter. Adults managing anxiety feel notably worse during darker months.
This isn’t a coincidence. It’s a nervous system reaching its reserve capacity limit.
Some people thrive year-round because their nervous systems are resilient to environmental changes. Others struggle seasonally because their systems lack that foundational capacity.
And that requires looking at what happened earlier, much earlier, in life.
How Early Life Stress Creates Seasonal Depression Vulnerability
The connection between early childhood and adult seasonal depression becomes clear when you understand how nervous system vulnerability develops.
The “Perfect Storm” Framework
At PX Docs, we call the combination of factors that create nervous system dysregulation and dysautonomia the “Perfect Storm.” This describes how a series of events and stressors, often beginning early in life, create a cascading effect that disrupts normal nervous system development.
The Perfect Storm isn’t the result of one single cause. It forms from an accumulation of stressors impacting the nervous system during its most critical developmental windows. Each factor alone may be manageable, but together they disrupt normal development and set the stage for chronic health challenges in children.
Four components appear consistently:
- Prenatal Stress: Maternal anxiety, depression, or chronic stress exposes the developing nervous system to elevated cortisol and stress hormones. The connection between mother and baby is neurological. When mom experiences stress, the baby’s nervous system is bathed in those stress signals during the most impressionable period. This “programs” the system to expect a stressful environment.
- Birth Trauma: Interventions like cesarean sections, forceps delivery, vacuum extraction, or extended labor can create physical stress to the infant’s upper cervical spine and vagus nerve pathway. The pulling, twisting, and pressure during birth—while often medically necessary—can affect delicate nervous system structures at the skull’s base. This isn’t about blame; it’s about understanding the physical and neurological consequences of these often life-saving interventions.
- Early Childhood Stressors + Toxic Overload: The months following birth often bring colic, reflux, constipation, frequent ear infections, and antibiotics. Each adds stress to a vulnerable system. Antibiotics disrupt the gut microbiome, directly affecting immune function and nervous system regulation. Chronic digestive issues signal that the Autonomic Nervous System isn’t coordinating properly. These aren’t temporary—they’re warning signs.
- Delayed Motor Development: Missed milestones, sensory processing challenges, and coordination challenges signal that the nervous system isn’t developing as it should. When children skip crawling, walk late, or struggle with balance, it reveals that neurological organization isn’t progressing as it should.
The “Perfect Storm” is often already brewing by 3, 6, 12, or 18 months. Long before diagnostic labels appear, the nervous system shows signs of stress.
The Neurological Cascade
The “Perfect Storm” unfolds in stages.
- Stage 1: Birth trauma or prenatal stress triggers sympathetic activation. The gas pedal gets pressed. For most babies, this would be temporary. For some, the system doesn’t return to baseline. The nervous system gets “stuck” in sympathetic dominance. The brake pedal doesn’t engage. This baby can’t rest deeply, can’t digest efficiently, can’t regulate temperature well. Parents describe “high needs babies.”
- Stage 2: This is often completely overlooked as simply the “Terrible Two’s + Three’s” where daily struggles with sensory overload, transitions, development, and behavior are dismissed as something “all kids go through” and things they’ll just “grow out of” over time. But most parents report feeling something was “off” all along deep within their gut, and when they start to learn about nervous system dysregulation and subluxation, it all starts to make more sense.
- Stage 3: Multi-system dysfunction emerges. Digestion breaks down. Immune function dysregulates. Sleep suffers. Furthermore, the disruptions to sensorimotor integration and delayed motor development really start to cause trouble and lead to developmental delays overall, with additional things like speech, communication, socialization, and emotional regulation.
- Stage 4: By ages 3-7, diagnostic labels emerge as they start to struggle in school and socially. The same nervous system dysfunction manifests differently. Some get an Autism Spectrum Disorder Diagnosis, others ADHD, and still others end up with anxiety, Sensory Processing Disorder, or chronic health conditions.
The key take-home point – the child doesn’t “develop” ADHD at age 7. The nervous system vulnerability and imbalance were there all along. The signs just become more obvious as life demands increase.
The same nervous system that couldn’t regulate as a baby can’t handle school demands, social interaction, and environmental stress. And it definitely can’t handle seasonal transitions.
Restoring Nervous System Resilience: A Different Path Forward
When you understand that seasonal depression and emotional instability are really expressions of nervous system dysregulation and lowered resilience rather than simple chemical imbalances, a different approach to helping those who struggle with them becomes readily available.
By addressing the foundational root cause of nervous system dysregulation, we can then work to hold off the common pitfalls of seasonal depression, and also hope to keep children with autism, ADHD, anxiety, PANS/PANDAS, and chronic immune challenges from backsliding during the winter months as well.
Understanding Subluxation and Neurological Dysfunction
In Neurologically-Focused Chiropractic Care, we focus on subluxation, which refers to nervous system interference or dysfunction, not structural spinal misalignment. This distinction is critical.
Subluxation describes a state of nervous system dysfunction, dysregulation, and dysautonomia – terms that all mean the same thing, really. The most common place that subluxation and neurological interference occur within the neurospinal system is in the upper cervical and brainstem region, where the brainstem transitions to the spinal cord and where the vagus nerve pathway begins.
When the nervous system experiences this interference—often beginning with birth trauma and compounded by early life stressors—it affects how the entire body functions and adapts. Communication between the brain and body becomes disrupted. The Autonomic Nervous System struggles to shift between sympathetic and parasympathetic states. The vagus nerve, which should be coordinating digestion, heart rate, immune response, and nervous system regulation, can’t function optimally.
This isn’t about bones being “out of place.” It’s about neurological function—how well signals travel between the brain and the body.
When that communication doesn’t function optimally, the nervous system gets stuck in sympathetic dominance. The gas pedal stays stuck on. The brake pedal doesn’t engage. And adaptation to seasonal shifts and everyday stress becomes increasingly difficult.
INSiGHT Scanning: Objective Nervous System Assessment
At PX Docs, we use advanced INSiGHT scanning technology to objectively measure nervous system function. Unlike simply tracking symptoms or looking at blood work for nutritional deficiencies, these scans look deeper into the core neurological dysfunctions that trigger the cascade of physiological effects that can lead to tension, exhaustion, and emotional dysregulation commonly experienced with Seasonal Depression.
These scans provide baseline measurements and allow tracking of objective changes and improvements as care progresses. Parents and patients can see the nervous system shifting from red + blue (dysregulated) zones to green + white (balanced) zones. It’s personalized data showing each individual patient’s specific subluxation and dysfunction pattern.
It’s important to note that this technology does not diagnose medical conditions, and Neurologically-Focused Chiropractic Care is certainly not a treatment or cure for Seasonal Depression or any other condition, not even back pain. Instead, these INSiGHT Scans help us track down the root cause of nervous system dysfunction and dysregulation, and build customized care plans and adjusting protocols to help shift the nervous system back into a state of balance, regulation, and resilience.
How It Helps
When we work to remove and clear subluxation and neurological dysfunction, the nervous system naturally returns to a balanced, regulated state. When this shift occurs, it restores optimal resilience and adaptability, and it’s far easier for the patient to then handle the seasonal transitions, holiday chaos (that also comes with winter), and more.
When under regular Neurologically-Focused Chiropractic Care, patients can spend less time stuck on the gas pedal, dealing with constant tension and exhaustion, and instead experience more “brake pedal” tone, with the nervous system having more energy and reserve capacity.
Think of it like each adjustment not only helps release and clear out that stuck sympathetic stress, but most importantly, it recharges your body’s battery and gets you back to full power once again. Simply put, if the winter months and lack of daylight, sunshine, Vitamin D, and outdoor activity mean our battery drains faster and recharges less easily – get in and get adjusted more frequently and stay ahead of the curve that way!
Supporting Nervous System Health Through Seasonal Changes
Alongside Neurologically-Focused Chiropractic Care, several lifestyle strategies support nervous system health during seasonal transitions.
- Consistent Sleep-Wake Cycle: Your circadian rhythm thrives on consistency. Going to bed and waking at the same times daily—even on weekends—helps your nervous system maintain its internal clock despite changes in external light.
- Morning Sunlight Exposure: Natural light within the first hour of waking helps boost serotonin and regulate circadian rhythm. Aim for 15-30 minutes outdoors. If natural light is insufficient, light therapy boxes providing 10,000 lux can supplement.
- Anti-Inflammatory Nutrition: Omega-3 fatty acids from fish, flaxseed, and walnuts support brain health and mood regulation. Reducing sugar and processed foods decreases inflammation. Focus on whole foods, healthy fats, and quality proteins.
- Gentle Movement: For nervous systems under stress, high-intensity exercise can actually add more stress. Gentle movement like walking, yoga, or swimming supports regulation without overwhelming. Consistent moderate activity proves more beneficial than sporadic intense workouts.
- Stress Management Practices: Deep breathing directly activates the parasympathetic nervous system—engaging that brake pedal. Mindfulness and meditation support emotional regulation. Even 10-15 minutes daily makes a measurable difference in autonomic function.
- Social Connection: Isolation worsens seasonal depression significantly. Regular contact with friends, family, and community supports the nervous system. Schedule social activities even when motivation is low.
- Limiting Nervous System Depressants: Alcohol is a nervous system depressant that worsens mood and disrupts sleep. Caffeine increases sympathetic activation, adding to anxiety and interfering with sleep. Consider reducing or eliminating both during the winter months.
These strategies aren’t about perfection; they’re about regulation and adaptation. Do your best to take care of yourself and your nervous system during these winter months, and you’ll be sure to come out stronger and more resilient on the other side.
From Surviving Winter to Thriving Year-Round
Seasonal depression isn’t simply a chemical imbalance that some people are genetically programmed to struggle with, and it’s not something that should force you to move to Florida or South America. It’s a sign the nervous system has lost some of its reserve capacity and resilience.
For most children and adults, the dysfunction and nervous system challenges set in long before daylight saving time kicked in, and the lack of sunshine and outdoor activities just compounds an already existing problem rather than creating a new one.
But here’s the good news – the nervous system is designed to heal, recover, and regulate!
When they get under regular Neurologically-Focused Chiropractic Care, most people can’t believe how much of a change just a few adjustments can make to get their sleep and energy back online, and then it’s all uphill improvements from there.
If you want to have your family stay healthy, energized, and thriving all winter long – make sure that regular chiropractic care is the foundation of your health plan, along with the other supportive strategies discussed throughout this article. If Neurologically-Focused Chiropractic Care is new to you, we encourage you to visit our PX Docs directory to find your local practice and get started right away!
