Heat, whether it comes in the form of an unseasonably hot day in a cooler month, during normal summer weather or as a result of a hot artificial environments has health significance in TCM. People are considered to be more accident prone, have headaches more often, suffer “hot-blood” conditions like psoriasis, suffer more from cardiac conditions, febrile diseases and insomnia, when exposed to heat and hot weather.
Psychological illness can be exacerbated in the heat too, people tend to be more manic and excitable when it is hot and crime waves have been known to correspond with heat waves. Many become reckless in the pursuit of having a good time in summer, in TCM summer is the season of accidents. Just as the heat can quicken your pulse, so too do “heat causing” food and drink like alcohol, coffee, chilli, chocolate and drugs that rev you up like ice and speed. In Summer time people are more sociable, venture into nature and celebrate alot. In Australia more babies are born in August and Serptember than in the other months of the year, in TCM Summer is the season of joy.
People who dislike the heat often have a tendency to suffer from the energy states listed above just as people who prefer summer to winter often find that things like their osteo arthritis and blood circulation worse when it is cold. There is a feature of perceived heat in TCM too, where a “full heat” condition like heat stroke, hyperthyroidism or malaria does raise your body temperature, “empty heat” often does not.
In TCM empty heat is viewed as a condition caused by deficient body fluids rather than a fever, in my time as a nurse I encountered quite a few elderly people who would kick their blankets off and complain of feeling too hot even when the air temperature was not particularly warm. These poor souls often looked emaciated (due to chronic dehydration) and were flushed across the nose and cheeks (malar flush). They even looked dried out but would rarely drink water when it was offered, much to the frustrations of the nurses and doctors looking after them.
Empty heat (Yin deficiency) can be experienced by younger people too in the form of AIDS and Lupus. Whether heat is full or empty when you suffer from it it makes it hard to properly relax and be still. Burn out from living a frantic life style for too long is regarded as a heat condition in TCM also.
The five pernicious climates (cold, damp, dryness, wind and heat) interact with each other, heat and damp cause “hot damp” conditions- high humidity during monsoon can literally drive people mad who are not acclimatised to it because the moisture in the air will not allow your sweat to dry and cool you. When cold and wind combine the cold and flu season starts and wind dryness plays havoc with allergy sufferers.
In TCM so long as the transition from one season to the next is gradual rather than sudden and weather extremes do not occur we adapt and are less susceptible to illness.