Seasonal depression tricks the mind!
I wake up early, as I always do. The morning routine is intact, unchanged, almost automatic. And yet, for weeks now, something has been off. Energy is scarce, motivation feels thin. The familiar internal pull towards movement, challenge and curiosity has faded. There is no obvious sadness, just a dull absence where drive and enthusiasm used to live.
What is unsettling is not simply feeling tired, but feeling unlike myself. Activities that normally feel instinctive now require negotiation. The sports I love no longer spark anticipation. The body resists movement. The sofa and blanket exert an inexplicable gravitational force. Social plans feel optional at best, burdensome at worst.
The questions creep in: Why don’t I want to move? Why does rest feel compulsory rather than restorative? Why does going out feel harder than staying in? And perhaps the most unnerving question of all: where has my energy gone!?
These thoughts feel personal, even existential. But what if this is not a loss of self, ambition or meaning? What if it is something quieter, more biological and far more common than we tend to admit?
The answer
Seasonal depression, clinically referred to as Seasonal Affective Disorder (SAD), is often reduced to a story about dark mornings and low vitamin D. That explanation is convenient, but it misses the deeper and more unsettling truth: seasonal depression does not simply lower mood. It alters perception, memory, motivation and belief. It changes what the brain predicts about the future and how the body interprets safety, effort and hope.
People experiencing seasonal depression often describe it not as sadness, but as a sense that life has become heavier, narrower and more effortful. The world feels less responsive, plans seem pointless and relationships feel distant. Importantly, these thoughts do not arrive as intrusive or obviously irrational. They feel reasonable, even insightful. That is the trick.
The Brain in Low Light
From a neuroscience perspective, seasonal depression begins with light, but it does not end there. Light is the primary regulator of the circadian system, governed by the suprachiasmatic nucleus in the hypothalamus. When daylight shortens, this system loses precision. Melatonin secretion extends further into the morning, while cortisol, which normally rises to mobilise energy and attention, becomes blunted or delayed.
This mismatch creates a body that is biologically out of phase with the social world. People wake feeling unrested, cognitively foggy and emotionally flat, even after adequate sleep. Matthew Walker, in Why We Sleep, notes that disrupted circadian rhythms impair emotional regulation long before they affect conscious mood. The brain becomes less capable of emotional updating, meaning negative information lingers longer and positive signals fail to register fully.
Functional imaging studies show reduced activity in the prefrontal cortex during depressive states, particularly in areas responsible for cognitive flexibility and future planning. At the same time, the default mode network becomes more dominant. This network, associated with self-referential thinking and rumination, encourages the mind to loop inward, replaying concerns rather than engaging with the external world.
In simple terms, the brain shifts from exploration to conservation.
What Seasonal Depression Makes Us Believe
One of the most under-recognised aspects of seasonal depression is how convincingly it shapes beliefs. People often report thoughts such as this is just who I am now, I have lost my drive, or nothing really excites me anymore. These beliefs feel like conclusions drawn from evidence, not symptoms of a mood disorder.
Cognitive psychology offers an explanation. Depression alters what Aaron Beck called the cognitive triad: the way we view ourselves, the world and the future. In seasonal depression, this shift is subtle and often mistaken for realism. The future feels empty rather than threatening. The self feels inefficient rather than worthless. The world feels slow rather than hostile.
Lisa Feldman Barrett’s work in How Emotions Are Made adds another layer. Emotions are not passive reactions but predictions based on past experience and bodily signals. When the body consistently sends signals of low energy, heaviness and withdrawal, the brain predicts a world that requires less action. Motivation drops not because the person has changed, but because the brain is economising.
This can lead to a particularly deceptive belief: that withdrawal is wisdom. Social plans feel draining, ambition feels naive and rest begins to look like the only sensible response. Over time, this reinforces itself. Less action produces less reward, which confirms the brain’s prediction that effort is not worth it.
Neurochemistry Without the Buzzwords
Serotonin is often mentioned in discussions of seasonal depression, but rarely with nuance. Research shows that serotonin transporter activity increases during winter months, meaning serotonin is cleared from synapses more quickly. The result is not dramatic sadness but emotional flattening, reduced reward sensitivity and increased sensitivity to effort.
Dopamine is equally important here. Dopamine is not the pleasure chemical it is often made out to be; it is the molecule of anticipation and motivation. Reduced daylight and disrupted sleep dampen dopaminergic signalling, particularly in the mesolimbic pathway. The future stops pulling us forward.
This helps explain why people with seasonal depression often function well in obligatory tasks but struggle with self-initiated ones. They can meet deadlines but cannot start personal projects. They attend work but cancel social plans. The brain is capable, but it no longer expects reward.
Evolutionary and Predictive Theories
From an evolutionary perspective, seasonal withdrawal may once have been adaptive. Reduced energy expenditure during winter would have conserved resources when food was scarce and daylight limited. Randolph Nesse and other evolutionary psychiatrists suggest that low mood can function as a signal to reduce risk and effort under unfavourable conditions.
The problem is that modern environments do not allow for true seasonal slowing. Artificial light, fixed work schedules and constant cognitive demand mean the body enters a conservation mode while the world continues at full speed. The resulting mismatch creates frustration, guilt and self-criticism, which deepen depressive thinking.
Predictive processing theories frame this differently. The brain is constantly predicting the cost and reward of action. In seasonal depression, the prediction error system becomes conservative. It assumes high effort and low return. New experiences are filtered through this expectation, which makes change feel unlikely and improvement implausible.
This is why reassurance rarely helps. Telling someone with seasonal depression that spring is coming does little, because their brain is not estimating time incorrectly. It is estimating energy incorrectly.
The Body’s Role
Seasonal depression is not confined to the brain. Immune activity shifts in winter, with increased inflammatory markers in some individuals. Inflammation is known to reduce motivation and increase fatigue, a phenomenon sometimes called sickness behaviour. This is not metaphorical. The body behaves as if it needs to withdraw to heal.
Appetite changes, particularly cravings for carbohydrates, are also biologically driven. Carbohydrates temporarily increase tryptophan availability in the brain, which can modestly boost serotonin. What looks like lack of discipline is often an unconscious attempt at regulation.
Even posture changes. People move less, sit more and adopt more closed body positions. Research in embodied cognition suggests that this feeds back into emotional experience, reinforcing low-energy states.
Why It Feels So Personal
Perhaps the most painful aspect of seasonal depression is how personal it feels. Because it arrives gradually and aligns with external conditions, people often interpret it as a character flaw or a loss of meaning. They question their choices, relationships and identity. In Lost Connections, Johann Hari emphasises that depression often reflects disconnection from rhythm, purpose and environment rather than purely internal pathology. Seasonal depression is a particularly literal example of this disconnection.
The mind does not announce, Your neurobiology has shifted. It says, Something about your life is wrong. And unless we understand the mechanisms, we tend to believe it.
Seeing the Trick for What It Is
Understanding seasonal depression does not magically dissolve it, but it changes the relationship we have with our thoughts. When the brain’s predictions are recognised as state-dependent rather than truth-dependent, self-trust can slowly be rebuilt.
Seasonal depression is not just low mood caused by winter. It is a temporary reconfiguration of brain, body and belief, designed for a world that no longer exists. The danger lies not in the symptoms themselves, but in the stories the mind tells to explain them. And those stories, convincing as they feel, are not prophecies. They are weather.
