The multilayered nature of seasonal affective disorder

Physiological Mechanisms

At the biological level, SAD appears to involve several interconnected systems. The reduced sunlight in winter disrupts our circadian rhythms—our internal biological clock that governs sleep-wake cycles, hormone release, and mood regulation. Light entering the eyes signals the suprachiasmatic nucleus in the brain, which orchestrates these rhythms.

Winter's darkness also affects neurotransmitter production. Serotonin, our "feel-good" neurotransmitter, relies partly on sunlight exposure for synthesis. Lower serotonin levels correlate with depressive symptoms. Simultaneously, melatonin production increases in darkness—melatonin makes us sleepy and withdrawn. In winter, we're essentially producing more of a drowsiness hormone while making less of a mood-stabilizing one.

There's also the vitamin D connection. Sunlight on skin synthesizes vitamin D, which influences serotonin activity and numerous other physiological processes. Some researchers view winter depression partly as a vitamin D deficiency state.

Psychological and Emotional Dimensions

Beyond pure biology, there's something psychologically challenging about winter's contraction. The shortened days create a literal narrowing of possibility—less time for outdoor activities, social gatherings, spontaneous encounters. This environmental restriction can mirror and amplify feelings of internal constriction.

The loss of light might also deprive us of natural mood regulation strategies we don't consciously recognize. That morning sunlight, the afternoon walk, the evening twilight—these aren't just pleasant experiences but scaffolding for emotional stability. Remove them, and some people's mood architecture becomes unstable.

There's also the anticipatory dread some people develop—"winter is coming" becomes a personal psychological threat, creating anxiety that precedes and possibly worsens the actual depressive symptoms.

Mythic and Archetypal Perspectives

Across cultures, winter has been understood as a time of death and dormancy, a necessary descent before renewal. In Greek mythology, Persephone's annual descent to the underworld explains winter—her mother Demeter's grief causes the earth to become barren. This isn't just an explanatory myth; it suggests winter depression might be a natural, even archetypal human response to darkness.

Many traditions view winter as a time for introspection, going inward when the outer world contracts. From this perspective, SAD might represent a mismatch between modern expectations (maintain summer-level productivity year-round!) and an older biological-psychological rhythm that says "winter is for rest, reflection, slowness."

The Jungian analyst might see SAD as the psyche's attempt to force a necessary descent—into shadow work, into rest, into the "dark night of the soul" that precedes transformation. Our culture's resistance to this natural slowing, the demand to stay bright and productive, might make the experience pathological rather than simply uncomfortable.

Some indigenous traditions speak of honoring winter as a teacher—the season that shows us how to survive scarcity, how to find light within darkness, how to wait faithfully for return. When we pathologize this entirely, we might miss what the darkness is asking of us.

An Integrated View

Perhaps SAD exists at the intersection of all these levels. We're animals with neurochemistry shaped by millions of years of light-dark cycles, but we're also meaning-making creatures navigating cultural expectations and archetypal patterns. Modern life—with its artificial light, indoor work, and relentless pace—may leave us biologically dysregulated while also cutting us off from ritual and community structures that once helped humans weather winter psychologically.