Badly designed lighting systems could be preventing a good night's sleep, according to a project being presented at the Health Protection Agency's annual conference - Health Protection 2010 - at the University of Warwick today.

Scientists at the HPA's Centre for Radiation, Chemical and Environmental Hazards are investigating how the changing spectrum of light we are exposed to during the day affects our health.

Poorly designed artificial light systems together with spending too little time outdoors can reduce levels of the body clock hormone melatonin causing sleep disruption.

Dr John O'Hagan, leader of the HPA's Laser and Optical Radiation Dosimetry Group, said: "The spectrum of sunlight changes during the day so the amount of blue light declines as we approach night time. People have evolved to react to this cycle so that the level of melatonin builds up as we approach night time causing us to feel sleepy. If we get a very different pattern of light over the day and into the evenings, our health can be affected."

The project is initially researching the level of blue light at care homes for the elderly as well as in houses and hospitals. It also aims to investigate the potential link between exposure to artificial blue light at night and sleep disruption.

Dr O'Hagan said: "We believe the elderly could benefit most from the findings as a large proportion report difficulties with sleeping. They often have restricted access to time outdoors and their eye lenses gradually yellow over time, which reduces exposure to blue light."

He added: "We know that proper sleep patterns are important to people's health and mental well being, so it may be possible to improve people's health by making relatively simple improvements to lighting systems in care homes."

The research in hospitals aims to reveal how the sleep patterns of shift workers are affected by artificial lighting. The group will also investigate how patient recovery could be affected.

Dr O'Hagan added: "We hope this information together with the work in care homes and domestic properties will provide a compelling argument for further investigations, which will compare the health of people with differing exposures to blue light."

Notes

- The study, initially lasting two years, is funded by the Health Protection Agency and will be carried out by scientists in the Physical Dosimetry - Laser and Optical Radiation Dosimetry Group.

- As well as enabling vision, the eyes provide non-visual information via photoreceptors in the retina, known as 'intrinsically photosensitive retinal ganglion cells' (ipRGCs). The Supra Chiasmatic Nuclei synchronises the secretion of melatonin from the pineal gland into the blood stream.

- Exposure to blue light in the evening suppresses the onset of the production of melatonin. Melatonin should normally rise in the evening and the timing of this rise is controlled by the internal body clocks, but the presence of blue light can temporarily override this onset and gradually shift the internal timing of melatonin production.

- The Surrey Sleep Research Centre is to collaborate in the research.

Source:
Health Protection Agency