Our body temperature, typically around 98.6°F (37°C), is a vital indicator of overall health. While often considered a fixed point, it represents an average. Your actual body temperature can vary by a degree or two throughout the day, which is a normal occurrence. These minor shifts reflect the body’s continuous efforts to maintain internal balance and respond to various internal and external factors.
How Your Body Regulates Temperature
The body possesses a sophisticated internal system for maintaining a stable core temperature, known as thermoregulation. The hypothalamus, a small region in the brain, acts as the body’s thermostat. It continuously monitors and adjusts temperature to keep it within an optimal range.
When temperature deviates from its set point, the hypothalamus initiates responses to generate or dissipate heat. If too warm, blood vessels widen to release heat, and sweat glands activate for cooling. If too cold, blood vessels constrict to conserve heat, and muscles may shiver to generate warmth. These actions keep the body’s core temperature stable despite environmental changes.
Everyday Influences on Body Temperature
Beyond internal regulation, daily activities and external factors can cause temporary shifts in body temperature. Environmental conditions, such as hot or cold weather, directly influence heat gain or loss. Wearing inappropriate clothing can also affect temperature by impeding or enhancing heat exchange. Physical activity generates heat as muscles work, leading to a temporary rise in body temperature.
The time of day also plays a role, as body temperature naturally fluctuates with your circadian rhythm. It is lowest in the early morning and highest in the late afternoon or early evening. Certain foods and drinks, like spicy dishes, can trigger temporary changes. Stress and emotions can also cause temperature shifts, with anxiety potentially leading to temporary increases.
Health Conditions and Medications That Affect Temperature
Persistent or significant temperature fluctuations can signal underlying health conditions or medication side effects. Infections commonly cause fever, as the immune system raises body temperature to combat viruses or bacteria. This elevation is part of the body’s defense, as many pathogens struggle to thrive at higher temperatures.
Hormonal imbalances can also impact temperature regulation. Thyroid disorders affect metabolism; hyperthyroidism can cause increased heat sensitivity, while hypothyroidism can lead to feeling cold. Menopause often brings hot flashes, sudden sensations of warmth and sweating, due to fluctuating estrogen levels affecting the brain’s temperature control center.
Autoimmune conditions, where the immune system attacks healthy tissues, can also disrupt temperature regulation. Conditions like lupus can cause fevers due to inflammation, while others may lead to heightened sensitivity to cold or heat. Some medications can interfere with the body’s ability to maintain a stable temperature. Certain antidepressants, including SSRIs and TCAs, can affect the hypothalamus and sweating, potentially leading to heat intolerance or increased body temperature.
When to Consult a Doctor
While minor temperature fluctuations are normal, certain signs indicate a need for medical evaluation. Contact a healthcare provider if your temperature reaches 103°F (39.4°C) or higher. For adults, a fever persisting longer than three to five days warrants medical attention.
A low body temperature, or hypothermia (below 95°F / 35°C), is a medical emergency. Symptoms include shivering, slurred speech, confusion, clumsiness, or very low energy. Seek immediate medical care if temperature changes are accompanied by concerning symptoms like severe headache, stiff neck, rash, difficulty breathing, persistent vomiting, or mental confusion. These symptoms, with either high or low temperatures, require prompt medical assessment.