The association could have special relevance in care homes and intensive care units where lights are almost never switched off, say researchers from Leiden University Medical Centre in The Netherlands.
They reckon that 75 per cent of the world’s population is exposed to artificial lighting during the night, and this interferes with the natural light-dark cycle that’s so important for regulating and maintaining health.
Losing this natural circadian rhythm can trigger a range of diseases normally associated with unsteadiness and frailty in the elderly, such as inflammation, muscle loss and osteoporosis.
Although people might think that our exposure to light would have a neutral effect on health, countless studies are showing that we have evolved to need periods of darkness, say the researchers.
Their own research has centred on laboratory mice that were exposed to constant light 24 hours a day. The mice’s usual circadian patterns were affected by 70 per cent, and as a consequence, their bones started to show signs of deterioration, and it triggered a pro-inflammatory state that is normally seen only when someone is exposed to pathogens or other harmful stimuli.
The symptoms disappeared within two weeks after the mice started to experience a normal day and night cycle.