Light Timing & Brain Circuits: Norwegian Winter's Effect on Mood

Light Timing & Brain Circuits: Norwegian Winter's Effect on Mood

 

When I first read the research paper "Timing of light exposure affects mood and brain circuits" published in Translational Psychiatry, I had one of those moments where everything suddenly made sense. You know, when things make sense but there are "holes" in your understanding. I read this paper a few years back now, but it is equally as relevant today!

I remember back in 2010's, all those conversations with customers over the years. The personal trainer clients who came to me not just tired, but genuinely struggling with their mental health during Norwegian winters. The patterns I'd seen in my own life and my family's wellbeing. The research I'd been following about circadian biology and quantum health principles.

It all clicked into place.

This wasn't just about seasonal affective disorder or "winter blues." This was about fundamental biology being disrupted by our modern light environment - and for those of us in Norway, the problem is amplified by our extreme seasonal variations in natural light.

Let me break down what this research reveals, why it matters desperately for Norwegians, and what we can actually DO about it based on solid science, not wishful thinking.

Understanding the Research: Light Isn't Just About Vision

For most of human history, we thought light's primary function was vision. Sure, we knew about circadian rhythms and the sleep-wake cycle, but we understood that through a relatively simple model: light tells your brain when it's day, darkness tells it when it's night, and this controls your sleep timing.

Done. Simple.

Except it's not simple at all. And the research by Bedrosian and Nelson reveals just how profoundly complex - and important - light's role in mood regulation actually is.

The Discovery of ipRGCs Changed Everything

In 2002, researchers discovered a third type of photoreceptor in the mammalian eye: intrinsically photosensitive retinal ganglion cells, or ipRGCs for short (because nobody wants to say that mouthful repeatedly). I think I have mentioned them hundreds of times of the last few years, but only a handful of times have I used their true name.

These cells are fundamentally different from rods and cones - the classical photoreceptors that handle image-forming vision. ipRGCs contain melanopsin, a photopigment that makes them uniquely sensitive to blue light around 480nm. And critically, these cells project to completely different parts of the brain than the visual pathways.

ipRGCs send signals to:

  • The suprachiasmatic nucleus (SCN) - your master circadian clock
  • The lateral habenula - involved in processing disappointment, negative reward, and depression
  • The amygdala - fear, anxiety, and emotional processing
  • The ventral tegmental area (VTA) - dopamine production and reward processing
  • The locus coeruleus - norepinephrine production and arousal

See the pattern? These aren't vision centers. These are MOOD and EMOTION centers.

Light detected by ipRGCs is literally communicating directly with the parts of your brain that control how you feel emotionally. This happens completely separate from the visual information being processed by rods and cones. I mean, yes it is coming through the eyes, but in real terms, these signals are dealt with very differently.

What This Means in Practice

When you expose yourself to blue-rich light at night - from LED ceiling lights, computer screens, phones, tablets - you're not just "staying awake." You're directly stimulating brain circuits involved in mood regulation at a time when they should be quiet.

The Bedrosian and Nelson research documents multiple mechanisms through which mistimed light exposure affects mood:

Disrupted Neuroplasticity: Exposure to light at night reduces hippocampal neurogenesis (the creation of new neurons), decreases dendritic length and complexity in the prefrontal cortex, and reduces the density of dendritic spines. Translation: Your brain's ability to adapt, learn, and maintain healthy emotional regulation is being directly impaired. Think about kids!

Altered Neurotransmission: Light at night disrupts serotonin, dopamine, GABA, and glutamate systems. These are the exact neurotransmitter systems that essentially ALL antidepressant medications target. You can be taking medication to fix these systems while simultaneously disrupting them with your light environment. Think about the epidemic of mental health issues we are currently facing.

Clock Gene Disruption: Exposure to light at night blunts the amplitude of clock gene expression (PER, CRY, BMAL1, CLOCK). These genes don't just control sleep timing - they regulate cellular metabolism, DNA repair, inflammation, and countless other processes throughout your brain and body.

BDNF Reduction: Light at night reduces expression of brain-derived neurotrophic factor (BDNF), particularly in the hippocampus. BDNF is like fertilizer for your brain - it supports neuron growth, survival, and plasticity. Lower BDNF is consistently associated with depression.

Glucocorticoid Dysregulation: Mistimed light affects cortisol rhythms, potentially leading to hypercortisolemia (too much cortisol), which is observed in a subset of major depression patients.

And here's what makes this research so critical: These effects occur EVEN WHEN SLEEP ISN'T DISRUPTED. Nocturnal rodents exposed to dim light at night showed depressive behaviors without any sleep disruption. This isn't just about being tired. This is about light directly affecting emotional circuits in the brain. I have talked about the importance of curtains to block even external light sources as they get worse.

The Norwegian Context: We're Living in an Extreme Light Environment

Now let's talk about why this research matters so much specifically for us in Norway.

We experience what I call "double-jeopardy" when it comes to light exposure:

Winter Double-Jeopardy:

  1. Insufficient morning/daytime light exposure (weak daylight for only a few hours)
  2. Excessive evening artificial light exposure (LED lighting, screens, indoor illumination)

Summer Double-Jeopardy:

  1. Nearly constant daylight (in far northern regions, the sun doesn't set for weeks)
  2. Still using bright artificial light indoors when we should be experiencing natural dimming

Either extreme disrupts circadian function, but winter is particularly problematic for mood.

The Winter Light Deficit

During Norwegian winter, depending on how far north you are, you might only see weak daylight for 3-6 hours. And often that "daylight" is cloud-filtered, delivering maybe 1,000-5,000 lux on an overcast day compared to 10,000-100,000+ lux from direct sunlight.

Your circadian system NEEDS strong morning light to set properly. Without it:

  • Your SCN doesn't receive a clear "start of day" signal
  • Cortisol secretion doesn't peak at the appropriate time
  • Melatonin production timing drifts
  • Peripheral clocks throughout your body and brain become desynchronized
  • Mood-regulating neurotransmitter rhythms flatten out

The research is clear: Morning light exposure is just as important as avoiding evening light. Many Norwegians focus only on getting enough total light (buying SAD lamps, etc.) but pay no attention to WHEN they get that light.

The Evening Light Excess

Then, to compensate for limited daylight, we use bright artificial lighting all evening. Modern LED bulbs, optimized for energy efficiency, often have a color temperature of 4000-6000K - very blue-rich. Exactly the spectrum that most strongly activates ipRGCs and disrupts circadian signaling.

Add in screens - phones, tablets, computers, TVs - and you're getting even more blue light directly into your eyes. The research showed that exposure to just 5-40 lux of light at night is sufficient to:

  • Reduce hippocampal neurogenesis
  • Decrease BDNF expression
  • Alter neurotransmitter systems
  • Produce depressive behaviors in animal models

For reference, a typical smartphone emits over 40 lux. A standard living room has 100-300 lux. An iPad emits around 40 lux. We're drowning in circadian-disrupting light every evening.

The Sleep Cascade

While the direct effects of mistimed light on mood circuits are now understood, we can't ignore the sleep component either.

The research documents that nighttime light:

  • Suppresses melatonin (even very dim light - 0.15 lux from urban sky glow is sufficient in extreme cases.)
  • Increases sleep latency (time to fall asleep)
  • Reduces sleep quality and depth
  • Decreases slow-wave sleep oscillations important for memory and emotional processing

For Norwegians already struggling with circadian disruption from limited daylight, adding sleep disruption on top creates a perfect storm for mood disorders.

The Shift Work Crisis

The research highlights shift work as a particularly severe form of circadian disruption. In Norway, approximately 15-20% of the workforce is engaged in shift work.

The data is sobering:

  • Shift workers have significantly higher rates of depression
  • Prolonged shift work (20+ years) increases LIFETIME risk of major depression
  • Even short-term shift work alters mood
  • The risk is dose-dependent - more years of shift work = higher risk

Why? Because shift workers are:

  1. Exposing themselves to bright light during their biological night
  2. Trying to sleep during their biological day
  3. Constantly phase-shifting their circadian rhythms
  4. Disrupting every system that depends on circadian timing - which is basically EVERYTHING

The research showed that while bright light therapy during night shifts can improve alertness, it doesn't solve the fundamental problem. You're still forcing your brain to be awake when it should be asleep, and trying to sleep when it should be awake.

For shift workers, the solution isn't simple. But what we CAN do is minimize the circadian disruption through strategic light management.

The Developmental Concern: Children and Adolescents

Something the research emphasizes that terrifies me as a parent: Children and adolescents are MORE sensitive to the mood-disrupting effects of mistimed light than adults.

Young people today are experiencing unprecedented exposure to evening blue light:

  • 87% of women watch TV in the hour before bed
  • 36% of parents and 34% of children sleep with electronics in their room
  • Adolescents living in areas with high outdoor light pollution have stronger evening chronotypes

And the research shows:

  • Adolescents are more sensitive to melatonin suppression by light than adults
  • Early-life circadian disruption can have LONG-LASTING consequences
  • Mice exposed to dim light at night early in life showed increased anxiety as adults

We're conducting a massive uncontrolled experiment on the developing brains of an entire generation. And the research suggests we should be very concerned about the long-term mental health consequences.

The Biological Mechanisms: How Light Actually Affects Your Brain

Let me get a bit more detailed on the mechanisms, because understanding HOW this works makes it easier to understand WHY the solutions I recommend actually make sense.

Direct ipRGC Projections to Mood Centers (Don't worry about the names, just try to understand what is capable of being affected).

ipRGCs project directly to:

Lateral Habenula (LHb): This region is critically involved in processing negative emotions and "anti-reward." When you're disappointed or experience something negative, your LHb activates. Overactivation of the LHb is associated with depression - it essentially tells your brain "this isn't worth it, don't bother." Aberrant light exposure affects LHb function, potentially increasing depressive responses.

Medial Amygdala (MeA): Involved in processing emotional significance of stimuli, particularly fear and anxiety. ipRGC projections to the amygdala mean that light timing directly affects your anxiety responses and emotional reactivity.

Ventral Tegmental Area (VTA): A major dopamine-producing region involved in reward processing, motivation, and pleasure. Light affects VTA function, which impacts motivation and anhedonia (inability to feel pleasure) - core features of depression.

These direct projections mean that EVERY TIME you look at a screen at night, you're not just "keeping yourself awake." You're directly stimulating neural circuits that control whether you feel depressed or anxious.

My question then leads to: "If you continue to reinforce this networks and connections, do you then get withdrawals (with absence) or stronger pathways created via this method"

Indirect Effects Through Clock Disruption

The SCN acts as your master pacemaker, synchronizing clocks throughout your brain and body through both neural and hormonal signals. When mistimed light disrupts the SCN, it creates downstream chaos:

Peripheral Brain Clocks: Regions like the hippocampus, prefrontal cortex, and amygdala all have their own clock mechanisms. When these become desynchronized from the SCN (or from each other), the result is impaired function.

Hormone Rhythms: Melatonin, cortisol, thyroid hormones, sex hormones - all show circadian rhythms controlled by the SCN. Disrupting the master clock disrupts all of them. And these hormones profoundly affect mood.

Metabolic Rhythms: Your metabolism runs on a circadian clock. Disrupted circadian function leads to metabolic dysfunction, which ALSO affects mood. Depression and metabolic syndrome often occur together.

The Neuroplasticity Problem

Particularly concerning is what mistimed light does to your brain's structure.

The research documents:

  • Reduced hippocampal neurogenesis (fewer new neurons being born)
  • Decreased dendritic length in prefrontal cortex neurons
  • Reduced dendritic spine density in hippocampus
  • Impaired long-term potentiation (a form of synaptic plasticity important for learning and memory)

Translation: Chronic exposure to light at night is physically changing your brain's structure in ways that impair emotional regulation and cognitive function.

The hippocampus is critical for mood regulation, stress responses, and memory. The prefrontal cortex controls executive function, decision-making, and emotional control. When these regions show structural changes due to circadian disruption, mood disorders become more likely.

The Neurotransmitter Cascade

Multiple neurotransmitter systems show circadian rhythms and are disrupted by mistimed light:

Serotonin: The 5-HT system shows daily rhythms. Mistimed light disrupts these rhythms. Most antidepressants target serotonin. If you're disrupting serotonin rhythms with your light environment while trying to fix them with medication, you're working against yourself.

Dopamine: DA concentrations oscillate circadianly in the striatum and nucleus accumbens. The research showed that continuous lighting abolishes normal DA rhythms. This affects motivation, reward processing, and pleasure - all disrupted in depression.

Norepinephrine: NE also shows circadian patterns. The research found that aberrant light cycles altered NE levels. NE affects arousal, attention, and stress responses.

GABA and Glutamate: These also show circadian rhythms. GABA is your primary inhibitory neurotransmitter (calming), while glutamate is excitatory (activating). Balanced rhythms of both are necessary for proper brain function.

Light timing affects ALL of these systems simultaneously.

Does this seem like hyperbole? Perhaps a bit over the top? Well it's the truth and it's about time that people knew about it. Scientists have known about this for decades and they still push blue back lit screens, more "energy efficient" blue light street lamps and internal lighting. No one is looking after you apart from yourself.

What Actually Works: Evidence-Based Solutions for Norwegian Life

Alright, enough about the problem. Let's talk solutions. And I mean REAL solutions based on the biology, not just "try to get more sunlight" platitudes.

Morning Light Strategy: Set Your Clock Properly

The research is clear: Strong morning light exposure is critical for setting your circadian rhythm. But in Norwegian winter, natural morning light is often insufficient or it is too late (if there at all).

Solution: Strategic Use of Red Light Therapy

I use and recommend red light therapy panels for morning light exposure. Here's why this makes biological sense:

  1. Photonic Signal: While ipRGCs are most sensitive to blue light (~480nm), they DO respond to other wavelengths, including red and near-infrared. Exposing yourself to bright red/NIR light (660nm, 810nm, 850nm) provides a strong photonic signal to your circadian system. If you have some blues or further infrared waves then great, if not, don't worry.
  2. Mitochondrial Support: Unlike blue light, red and NIR wavelengths support mitochondrial function through cytochrome c oxidase activation. You're not just setting your clock - you're supporting cellular energy production.
  3. No Circadian Disruption: Red light in the evening doesn't disrupt melatonin or sleep the way blue light does. This means you can use the same device for both morning circadian support AND evening therapeutic applications. There are caveats as LUX (or brightness) does mater so I wouldn't use red light less than an hour before bed.

Protocol: 10-20 minutes of red light panel exposure upon waking, positioned at face level while you have morning coffee or breakfast. This provides the strong morning light signal your SCN needs to synchronize your circadian system.

For those who can't afford panels, GET OUTSIDE in whatever daylight is available, even if it's cloudy. Any natural light is better than none.

Evening Light Strategy: Protect Your Circadian System

This is where blue light blocking becomes non-negotiable.

The Three-Layer Approach:

Layer 1: Environmental Lighting
Transition your home to blue-free lighting after sunset (or after 6-7 PM in Norwegian winter when it's already dark).

Options:

The goal is to eliminate blue wavelengths from your environment while maintaining enough light to function safely.

Layer 2: Blue Blocking Glasses
Even with optimized environmental lighting, you need glasses because:

  • Other family members may use standard lighting
  • Screens still emit blue light
  • Appliance displays emit blue light
  • You can't control lighting outside your home

My recommendation: AfterDark™ glasses that block 98-99% of blue and green light (400-550nm range). Choose based on your needs:

  • Red lenses ("Moonlight") = maximum protection
  • Amber lenses ("Sundown") = strong protection with slightly more natural vision

Put them on 2-3 hours before your target bedtime. For most Norwegians, this means around 7-8 PM.

Layer 3: Screen Management
Minimize or eliminate screens in the evening. If you must use them:

  • Only with orange or red lens glasses on
  • In a room with red/amber lighting
  • Avoid high-brightness settings
  • Consider the All-Day Complete Protection system with interchangeable lenses for different times of day

For Families: Protecting Developing Brains

The research showed children are MORE sensitive to circadian disruption than adults. This isn't optional for kids - it's critical.

For Children:

My 9-year-old daughter uses this system. She's naturally in bed by 7:45-8:00 PM, no fights, no "I'm not sleepy" battles. The difference is the light environment.

For Shift Workers: Damage Control

If you work night shifts, you can't avoid circadian disruption entirely. But you CAN minimize it:

During Your Wake Phase (Even if It's at Night):

  • Use bright light for alertness (this is one case where blue light is acceptable, as you NEED to be awake)
  • Get red light exposure when you first wake up to help set your shifted rhythm

During Your Sleep Phase (Even if It's During Daytime):

On Your Days Off:
Try to maintain the SAME light exposure schedule rather than flipping back to a standard day rhythm. Constant shifting is worse than staying on your shifted schedule.

The Wavelength Factor: Why Red Light Is Different

The research documents that different wavelengths have different effects. Blue light (~480nm) most strongly activates ipRGCs and disrupts circadian function. Red light (>600nm) has minimal effect on ipRGCs but DOES support mitochondrial function through cytochrome c oxidase absorption.

This is why I emphasize red and near-infrared:

  • 660nm (red): Skin-level effects, collagen production, surface healing
  • 810nm (near-infrared): Deep penetration, brain support, neuroprotection
  • 850nm (near-infrared): Deepest penetration, mitochondrial support, systemic effects

These wavelengths provide therapeutic benefits WITHOUT disrupting circadian function. You can use red light therapy in the evening without affecting sleep.

The Bigger Picture: Public Health Crisis

The research ends with a sobering observation: The incidence of major depression is INCREASING in modern societies.

We know from the data:

  • Depression rates have increased dramatically over the past century
  • This increase correlates with adoption of electric lighting
  • Populations with limited electricity exposure (like the Amish) have remarkably low depression rates
  • Over 80% of humans now live under light-polluted skies

This isn't just individual health - it's a public health crisis.

And for Norwegians, we're at particularly high risk due to our extreme seasonal light variations. We can't change our latitude, but we CAN optimize our light environment.

The Long-Term Perspective: Neuroplasticity and Recovery

One hopeful aspect of the research: Many of the effects of circadian disruption are REVERSIBLE.

When animals were returned to normal light-dark cycles after chronic disruption:

  • Neurogenesis recovered
  • Dendritic structures regrew
  • Neurotransmitter rhythms normalized
  • Depressive behaviors resolved

This means it's never too late to start. Even if you've been living with circadian disruption for years, optimizing your light environment NOW can allow your brain to recover.

But it takes consistency. This isn't a quick fix. The research shows benefits accumulate over weeks to months of proper light timing.

Practical Implementation: Your 30-Day Action Plan

Week 1: Morning Optimization

  • Get outside within 1 hour of waking, even if cloudy (10-30 minutes)
  • OR use red light therapy panel for 10-20 minutes upon waking
  • Make this CONSISTENT - same time every day

Week 2: Evening Protection Starts

  • Get blue blocking glasses
  • Put them on 2-3 hours before bed
  • Begin dimming lights in your home after 7-8 PM

Week 3: Environmental Lighting Transition

Week 4: Screen Management

  • Reduce evening screen time
  • All remaining screen use only with blue blockers on
  • Aim for 1-2 hours screen-free before bed

Ongoing: Consistency Is Key

  • Maintain the same schedule 7 days per week
  • Track your mood, sleep quality, energy levels
  • Adjust timing as needed based on your response

Conclusion: Biology Doesn't Negotiate

The research is unequivocal: Timing of light exposure directly affects mood-regulating brain circuits through multiple mechanisms.

For Norwegians living with extreme seasonal light variations, this knowledge isn't academic - it's survival information. Our unique environment makes us particularly vulnerable to circadian disruption and mood disorders.

But we also have the knowledge and tools to address this:

  • Morning light exposure to set circadian rhythms
  • Evening blue light protection to preserve natural darkness signals
  • Strategic use of wavelength-specific lighting
  • Consistent timing protocols

Your brain evolved under specific light conditions. Modern life has changed those conditions faster than evolution can adapt. The result is widespread circadian disruption and mood disorders.

But unlike our ancestors, we understand the biology. We can use that knowledge to create light environments that support rather than disrupt our circadian systems.

The question isn't whether this matters. The research proves it matters profoundly.

The question is: Are you willing to make the changes necessary to protect your brain's emotional circuits?

References:

https://pmc.ncbi.nlm.nih.gov/articles/PMC5299389/

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