Infrared Sauna for Seasonal Affective Disorder

When daylight shrinks to a few hours and the sun stays low, millions of people notice more than the cold. Fatigue sets in. Mood flattens. Getting through the day feels like pushing through resistance. For roughly 10 million Americans, this pattern has a name: Seasonal Affective Disorder, or S.A.D.

S.A.D. is a clinically recognized subtype of depression, not simply the “winter blues.” It is driven by reduced light exposure, which disrupts the circadian rhythm, suppresses serotonin activity, and shifts melatonin production in ways that leave the body physiologically out of sync. Standard treatment centers on bright light therapy, and the evidence for it is strong. But a growing body of research suggests that infrared heat and red light therapy can meaningfully complement that approach, working through different physiological pathways to address the fatigue, mood disruption, and low energy that define the condition.

Why Light Alone Isn't Always Enough for S.A.D.

Bright white light therapy works primarily through the eyes, signaling the circadian system to reset the sleep-wake cycle. It is effective, particularly for the sleep disruption and low mood associated with S.A.D. But it doesn't address everything.

The physical heaviness of winter depression, the fatigue, muscle tension, low motivation, and brain fog, often persists even when circadian rhythms improve. That's where infrared heat and red light therapy come in. Each targets the body through a different mechanism, and together they create a more complete response to what shortened days actually do to the body.

How Infrared Saunas Support Mood and Serotonin

Infrared saunas use wavelengths of light that penetrate skin and tissue directly, raising core temperature through a process researchers call Whole-Body Hyperthermia, or WBH. Unlike traditional saunas, which heat the air around you, infrared heat works from the inside out, and that distinction has real neurological consequences.

As core temperature rises, warm-sensitive pathways in the skin signal the brain to release serotonin, the neurotransmitter most directly associated with mood stability and well-being [1]. Heat also stimulates the production of dynorphins, compounds that contribute to the calm, settled feeling many people describe after a sauna session, sometimes called the “afterglow.”

The clinical evidence is notable. In the UCSF HEATBed Study (2024–2025), participants with Major Depressive Disorder followed a protocol combining far-infrared sauna sessions with cognitive behavioral therapy. Eighty-six percent stopped meeting diagnostic criteria for depression by the study's end [2]. The result reflects a combined approach rather than sauna use in isolation, but it points clearly to the role that heat-based intervention can play in mood disorders. Earlier research published in JAMA Psychiatry found that a single WBH session produced measurable reductions in depressive symptoms lasting up to six weeks [3].

For people managing S.A.D., consistent infrared sauna use offers a way to actively support the neurochemical environment that winter depletes rather than waiting for the season to turn.

Red Light Therapy for Winter Depression: How It Works at the Cellular Level

Red light therapy works at a different scale, not the whole body, but the cell. Specific wavelengths of red light (around 660 nm) and near-infrared light (around 850 nm) penetrate the skin and stimulate the mitochondria, the structures within cells responsible for producing ATP, the molecule that powers cellular function [4].

For someone with S.A.D., this matters because one of the most persistent symptoms, fatigue and cognitive sluggishness that doesn't resolve with rest, is not simply a mood problem. It reflects reduced cellular energy output. Red light therapy addresses that directly, supporting the brain and body's capacity to function well even when daylight is limited.

A 2024 meta-analysis confirmed that transcranial photobiomodulation, a targeted form of red light therapy applied to the head, produces meaningful reductions in depressive symptoms [5]. One practical advantage: red and near-infrared wavelengths do not suppress melatonin, making evening use safe in a way that blue-spectrum bright light therapy is not.

Two Ways to Use Infrared Heat and Red Light Therapy Together

The decision of how to integrate infrared heat and red light therapy for S.A.D. doesn't have to be complicated. There are two practical approaches, depending on how you want to structure your wellness space.

The integrated approach: Arki

The Arki collection from JNH Lifestyles was designed around the convergence of infrared heat and red light therapy. Rather than treating them as separate modalities requiring separate sessions, Arki delivers both simultaneously within a single cabin, what JNH describes as 360° Light + Heat. Full-spectrum red and near-infrared panels work alongside infrared heaters so the cellular and neurological benefits unfold together. For those who want a seamless, time-efficient approach to dual therapy for seasonal depression, Arki is built for exactly that.

The modular approach: Tosi or Ensi + Red Light Panel

For those building a wellness practice incrementally, pairing a Tosi or Ensi infrared sauna with a JNH red light therapy panel achieves the same therapeutic combination through separate sessions. The sauna delivers the whole-body heat response; the panel, used before, after, or independently, handles the cellular energy component. This approach also allows flexibility in placement and timing based on your space and schedule.

Both paths deliver the core combination the research supports: sustained infrared heat for mood and nervous system benefits, paired with red light therapy for the cellular energy that winter consistently works against.

A Note on Chromotherapy

Chromotherapy is available as an add-on across the JNH sauna line, delivered via color bulb in Arki and Tosi, and via LED panel in Ensi. The delivery method differs, but the principle is the same: visible color wavelengths used to add a sensory dimension to a session.

The evidence base here is less developed than for infrared or red light therapy. Preliminary research suggests that specific colors may produce mild effects on mood and nervous system state: green associated with calm, blue with alertness, and warm tones with a sense of vitality [6]. It functions best as a sensory layer, a way to shape the feel of a session rather than a primary therapeutic tool.

A Suggested Protocol for Using Infrared Sauna and Red Light Therapy for S.A.D.

For those working through S.A.D. symptoms, a layered approach might look like this.

• Morning: 20–30 minutes of bright white light therapy to anchor the circadian rhythm. A red light therapy session can follow to support cellular energy and sharpen focus before the day begins.
• Afternoon or evening: An infrared sauna session, either an Arki session combining heat and red light simultaneously, or a Tosi or Ensi session paired with red light panel use. Use this window to support serotonin release, ease physical tension, and help the body transition toward rest.
• Consistency: Three to four sessions per week, sustained through the darker months, tends to produce more meaningful results than occasional intensive use.

Chromotherapy in green or amber tones can add a calming sensory dimension if your sauna includes the add-on.

Those with cardiovascular conditions, pregnancy, or medications that affect heat tolerance should consult a physician before beginning sauna use.

The Bigger Picture

S.A.D. is a physiological condition. It responds to the inputs the body is designed to receive, light, heat, and the biological signals these carry. Bright light therapy restores one of those inputs. Infrared heat and red light therapy restore others: the neurochemical environment that warmth supports, and the cellular energy that sunlight helps maintain.

Used together, these approaches offer something more complete than any single modality. Not a shortcut, but a considered, evidence-informed way to give the body what winter stops providing.