Turn off lights or risk health, hospitals warned

Hospitals have been warned to turn off their lights at night, or risk disrupting patient's circadian rhythms. A new study has found that exposure to artifical light all night could leave people susceptible to illness.

Researchers at the Leiden University Medical Centre in the Netherlands kept mice under constant artificial light for six months, prompting the rodents to develop a string of serious health problems.

We used to think of light and darkness as harmless or natural stimuli with respect to health. Our study shows that the absence of environmental rhythms leads to the severe disruption of a wide variety of health parameters

Professor Johanna Meijer - Leiden University Medical Centre 

The research, which was published in the journal Current Biology, is particularly worrying given that many hospital wards and care homes are kept lit throughout the night.

The mice were found to be suffering from muscle loss and the early signs of osteoporosis as a result of the constant light exposure. Some of the rodents were also developing serious immune system infections.

The mice were found to quickly recover after artificial light was switched to daylight.

‘We used to think of light and darkness as harmless or natural stimuli with respect to health. Our study shows that the absence of environmental rhythms leads to the severe disruption of a wide variety of health parameters,’ Professor Johanna Meijer, who led the investigation, commented. 

About 75 percent of the world’s population is exposed to light during the night and it is often common for intensive care wards to be kept illuminated until dawn.

The problem could also affect night shift workers in warehouses, who often work throughout the night under bright artificial lights.

‘The results of our study are possibly not surprising as life evolved under the constant pressure of the light-dark cycle,’ Professor Meijer concluded.

‘We seem to be optimised to live under these cycles, and the other side of the coin is that we are now affected by a lack of such cycles.’

  • Lux is hosting a special Lighting for Warehouses and Distribution Centres conference in Amsterdam on Thursday 29 September and Friday 30 September. It's free for all those involved with the management of storage and distribution. To view the details and register for a free place, click on the conference logo here.