Why matching your body temperature doesn't feel neutral
The intuition that 37°C air should feel "just right" treats the body like a cup of water left on a table, which settles at room temperature and stops changing. A living body never settles. It keeps producing internal heat through digesting food and moving muscles, and it stays near 37°C only because it continuously sheds that heat to the environment [2]. Comfort, on this view, is the state in which heat lost and heat gained are in balance — not the state in which the air happens to equal your core temperature [2].
So when the air itself is 37°C, the gap between your skin and the surroundings shrinks toward nothing, and the main channel for dumping heat weakens. The body then has to work harder to stay balanced, and that effort is what registers as distress or discomfort. The Siwa Oasis study frames it plainly: a person feels distressed when weather fluctuations exceed the body's capacity to regulate them [2].
What the discomfort actually is
The relevant signal is not damage but strain on regulation. The climate-comfort work treats comfort as a balance equation and discomfort as the point where environmental conditions outrun the body's ability to compensate [2]. That is why 37°C air can feel oppressive while 37°C water, which conducts heat away far faster, can feel pleasantly warm — the number is the same, but the heat flow is not.
The same logic appears in clinical settings from the other direction. In a study of fever treatment, axillary temperatures around 37°C were counted as fever in only a small share of cases, while 37.5°C was counted far more often — a reminder that 37°C sits at the boundary of "normal," and small excursions above it are where people start reporting discomfort [4]. The threshold is a regulatory one, not an absolute one.
When 37°C is exactly right
The number is not arbitrary. It is the temperature at which human biology is calibrated. A wearable in-ear device was deliberately engineered to expand at 36–37°C so it would conform to the skin comfortably and hold its position during movement [1]. Likewise, a crystallography study used 37°C as the "physiological condition" for examining how a rhenium complex binds to a protein, precisely because that is the temperature at which human proteins normally operate [3].
Bacteria read the same number as a signal. When E. coli is shifted from 23°C to 37°C, it rapidly reprograms gene expression — first toward stress responses and anaerobic strategies, then toward biosynthesis and host-defense genes — treating the warmth as a cue that it has entered a human host [5]. In each case 37°C is a set point or a trigger, not a comfort target for a person standing in it.
Why a fan helps even when the air is warm
If comfort is about heat flow rather than air temperature, then moving air, evaporating sweat, and cooler surfaces all matter more than the thermometer reading. The Siwa Oasis recommendations follow this logic: avoid crowding in enclosed spaces, cut car exhaust, use cooling in facilities, and schedule physically demanding work for the early morning when conditions are milder [2]. Each measure reduces the heat load or improves the body's ability to shed it, rather than trying to change the nominal temperature alone.
The honest limit of the evidence here is that these studies measure climate comfort, device behavior, protein stability, and bacterial response — not the sensory physiology of feeling hot. The explanation above is consistent with the comfort-balance framing in [2], but the precise sensory mechanism by which 37°C air is felt as uncomfortable is not directly tested in these papers.
Sources used in this answer
Body-Temperature-Responsive Balloon Actuator for Adaptive In-Ear Microneedle Electrode Deployment
A dual-layer balloon actuator expands at 36–37°C to give in-ear microneedle electrodes conformal, stable skin contact with reduced motion artifacts.
Effect of the Climate on Human Comfort in Siwa Oasis: A Study on Applied Climate
Human comfort depends on the balance between heat lost and gained, with 37°C as body temperature and distress arising when weather exceeds the body's capacity to regulate.
Body temperature protein X-ray crystallography at 37 °C: a rhenium protein complex seeking a physiological condition structure
A rhenium protein complex retained its covalent binding at physiological body temperature of 37°C, compared with a 100 K crystal structure.
Symptomatic intravenous antipyretic therapy: efficacy of metamizol, diclofenac, and propacetamol
In a fever-treatment study, axillary temperature counted as fever in 13% of cases at 37°C and 30% at 37.5°C.
A Shift to Human Body Temperature (37°C) Rapidly Reprograms Multiple Adaptive Responses in Escherichia coli That Would Facilitate Niche Survival and Colonization
Shifting E. coli from 23°C to 37°C rapidly reprogrammed gene expression, first toward stress and anaerobic responses and later toward biosynthesis and host defense.