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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Human body temperature | 4/4 | https://en.wikipedia.org/wiki/Human_body_temperature | reference | science, encyclopedia | 2026-05-05T07:29:23.993847+00:00 | kb-cron |
=== Normal === 36.5–37.5 °C (97.7–99.5 °F) is a typically reported range for normal body temperature.
=== Cold === 35.5 °C (95.9 °F) – Feeling cold, mild to moderate shivering. This can be a normal body temperature for sleeping. 35 °C (95 °F) – Threshold for hypothermia. Intense shivering, numbness and bluish/grayness of the skin. There is the possibility of heart irritability. 34 °C (93.2 °F) – Severe shivering, loss of movement of fingers, blueness, and confusion. Some behavioral changes may take place. 33 °C (91.4 °F) – Moderate to severe confusion, sleepiness, depressed reflexes, progressive loss of shivering, slow heartbeat, shallow breathing. Shivering may stop. The subject may be unresponsive to certain stimuli. 32 °C (89.6 °F) – (Medical emergency) – Hallucinations, delirium, complete confusion, extreme sleepiness that is progressively becoming comatose. Shivering is absent. Reflex may be absent or very slight. 31 °C (87.8 °F) – Comatose, very rarely conscious. No or slight reflexes. Very shallow breathing and slow heart rate. Possibility of serious heart rhythm problems. 28 °C (82.4 °F) – Severe heart rhythm disturbances are likely and breathing may stop at any time. The person may appear to be dead. 24–26 °C (75.2–78.8 °F) or less – Death usually occurs due to irregular heart beat or respiratory arrest; however, some patients have been known to survive with body temperatures lower than 12.7 °C (54.9 °F). The lowest recorded core temperature from a patient with accidental hypothermia who survived without neurological sequelae is 11.8 °C (53.2 °F). There are non-verbal corporal cues that can hint at an individual experiencing a low body temperature, which can be used for those with dysphasia or infants. Examples of non-verbal cues of coldness include stillness and being lethargic, unusual paleness of skin among light-skinned people, and, among males, shrinkage, and contraction of the scrotum.
== Effect of environment == Environmental conditions, primarily temperature and humidity, affect the ability of the mammalian body to thermoregulate. The psychrometric temperature, of which the wet-bulb temperature is the main component, largely limits thermoregulation. It was thought that a wet-bulb temperature of about 35 °C (95 °F) was the highest sustained value consistent with human life. A 2022 study on the effect of heat on young people found that the critical wet-bulb temperature at which heat stress can no longer be compensated, Twb,crit, in young, healthy adults performing tasks at modest metabolic rates mimicking basic activities of daily life was much lower than the 35 °C (95 °F) usually assumed, at about 30.55 °C (86.99 °F) in 36–40 °C (97–104 °F) humid environments, but progressively decreased in hotter, dry ambient environments. At low temperatures the body thermoregulates by generating heat, but this becomes unsustainable at extremely low temperatures.
== Historical understanding == In the 19th century, most books quoted "blood heat" as 98 °F, until a study published the mean (but not the variance) of a large sample as 36.88 °C (98.38 °F). Subsequently, that mean was widely quoted as "37 °C or 98.4 °F" until editors realized 37 °C is equal to 98.6 °F, not 98.4 °F. The 37 °C value was set by German physician Carl Reinhold August Wunderlich in his 1868 book, which put temperature charts into widespread clinical use. Dictionaries and other sources that quoted these averages did add the word "about" to show that there is some variance, but generally did not state how wide the variance is.
== References ==