[delian66]

That article is wrong. The quote that you gave, is contradicted in the last paragraph of the same article: >> Recent research by Dutch scientists found that by increasing skin temperature the sleep quality in elderly people could be enhanced.

Also the study, that the article links to [0] says:

By employing a thermosuit to control skin temperature during nocturnal sleep, we demonstrate that induction of a mere 0.4 degrees C increase in skin temperature, whilst not altering core temperature, suppresses nocturnal wakefulness (P<0.001) and shifts sleep to deeper stages (P<0.001) in young and, especially, in elderly healthy and insomniac participants. Elderly subjects showed such a pronounced sensitivity, that the induced 0.4 degrees C increase in skin temperature was sufficient to almost double the proportion of nocturnal slow wave sleep and to decrease the probability of early morning awakening from 0.58 to 0.04. Therefore, skin warming strongly improved the two most typical age-related sleep problems; a decreased slow wave sleep and an increased risk of early morning awakening.

[0] http://www.ncbi.nlm.nih.gov/pubmed/18192289?dopt=Abstract