Human Cold

The following is speculative reasoning about general 'colds' experienced around early winter periods. This can also apply when exiting a warm environment and suddenly entering a much colder one.

• Or, indeed, moving to a (much) warmer climate. 'Colds' can be suffered simply going on holiday to a sunnier and warmer climate.

Homeostasis is the human body's continuous attempt to maintain a stable core temperature: 37°C (98.4°F). The human 'cold' is not necessarily what it seems to be. Rapid temperature change between autumn and early winter places an extra burden on the system to maintain body temperature. The 'symptoms' of a cold manifest. The clammy, shivering, general aching and discomfort. It's not a cold, but body adaptation to rapidly changing conditions. Such 'feelings' can be confused and misinterpreted like excitement and anticipation or thirst and hunger. A glass of water might quell that feeling of hunger! Awareness of an alternative can be beneficial.

• The distinction between the one and the other is not always possible unless a conscious appraisal can make a valid determination

When the temperature is too hot, body overheating is the problem. Hyperthermia.

Hypothermia - too cold. The body is unable to adapt to changing conditions.

An infection is a different concept.

• Metabolism changes are not rapid, but adjustments do occur.

In a similar way, decompression sickness (the bends) is a result of a rapid reduction in external pressure between deep water and rising too fast to shallower water. Dissolved nitrogen in the blood bubbles out of solution causing extensive damage to the system. The slow dissolution of gas as the pressure increases with increasing depth is not in itself a problem, but the reverse must be controlled and is a slow process. Gradual decompression from depth to surface allows the body to release nitrogen slowly without consequence.

When at a high altitude, the rarity of oxygen in the atmosphere is dangerous. The human system has a finite range of conditions within which survival can be maintained. The combination of low oxygen levels (and pressure) and temperature has a serious effect on the human system. Too extreme and death will supervene. At moderate altitudes, acclimatisation is necessary for adaptation to the environment.

Even a moderate change in atmospheric temperature (up or down) has consequences. It's conceivable that the change in axial tilt and the resulting, but gradual, increase in global temperatures is a cause for 'cancer' (the term used to define uncontrolled growth). The human system is not capable of withstanding such change without consequence.