Professor Peter Hayes of the University of Alberta (Canada) analysed the records of 628 first heart attack patients and found that those in rooms on the south side of a hospital's cardiac intensive care unit tended to fare much better than those treated on the north side. The study showed that 39% of patients on the north side (which was much darker, with less sunshine) failed to survive compared to 21% on the sunnier south side.

The effect was particularly noticeable in women patients, supporting other research which had suggested that lack of daylight affected women's mental health more significantly than men's.

Ed.- (i) In 1996, the same team showed that clinically depressed patients in sunny hospital rooms fared far better than those in dull rooms.

(ii) Alternatives in Health's editor, Adam Jackson, pointed out that organisations could combat the adverse effects of lack of sunshine (termed Seasonal Affective Disorder (SAD)) by installing full spectrum lighting. He recommended Outside-in (Cambridge) Ltd. as a supplier (Tel: 01954 211955).

New born babies also benefit. There is evidence that jaundice, where the liver removes insufficient bilirubin from the blood, may be caused by low exposure to sunlight. Natural or artificial sunlight is certainly now the cure of choice after a chance discovery by a nurse in 1956. Infants in a sun-lit ward can receive over 27,000 lux, compared to babies in dull wards who may only receive 110 lux. The average levels of jaundice reflect this: 0.5% get jaundice in sun-lit wards, 17% in dull wards.

Sunlight therapy was a major medical tool against bacteria before it was replaced by antibiotics. Perhaps, now that resistances to antibiotics are developing due to their overuse and misuse, sunlight will regain favour as a non-invasive, powerful remedy.