That cheap, efficient way to beat the heat could be doing more harm than good.

FOX's Pat O'Neill has more:

Turning on that fan.... May defeat the purpose. A new experiment suggests electric fans could make older adults hotter, not cooler during extreme heat.

Researchers had eight seniors sit for two hours in a 107-degree chamber with a fan one day and without it another day. Their heart rates with the fan averaged 10 beats a minute more with body temperatures a half-degree higher.

They say it's because older people don't sweat as much, so they don't get the cooling affect of sweating, making them more prone to heat-related illnesses.

The report in the Journal of the American Medical Association notes that it was a very small sample size and more study is needed.

Pat O'Neill, FOX News.