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Coloured light helps elderly people to sleep better

Researchers at Aarhus University are studying the effect on the elderly of a special form of circadian rhythm lighting. The light changes colour during the day, and the first tests indicate that it can provide a better quality of sleep.

2015.08.31 | Kim Harel

Coloured artificial light can regulate our circadian rhythm and provide us with a better sleep quality. But how should the light be combined and interact with daylight? How strong should it be? What colour composition and heat balance are optimal? Could it be thought that the good mix is individual? Researchers are in the process of studying the full potential of circadian rhythm lighting in a pilot study among nursing home residents. (Photo: Colourbox)

Professor Poul Henning Kirkegaard wants a closer understanding of how coloured circadian rhythm lighting and its interaction with the surroundings and daylight can be incorporated into the architecture. He hopes that in the future we will be able to live in buildings that provide better sleep quality. (Photo: Anders Trærup)

In a pilot study conducted at a nursing home in Herning, Aarhus University researchers took the first step towards a deeper understanding of the importance of light for helping elderly people to sleep properly.

During a period of three weeks, they followed eighteen healthy nursing home residents and their sleep behaviour when subjected to circadian rhythm light that changes colour.

Come to a lecture (in Danish) on healing light at the Navitas Building during the Aarhus Festival.

Artificial lighting with great potential
The study indicates that artificial lighting in colours with different wavelengths can have a positive influence on the circadian rhythm.

“We know from previous studies that we can influence our sleep patterns by means of coloured light. The trick is to regulate our artificial lighting indoors to provide an optimal circadian rhythm. This can be relevant for elderly people in particular, because we produce less sleep hormone as we get older, and thereby have a poorer sleep quality. Circadian rhythm lighting has great potential that we haven’t yet investigated in depth,” says Professor Poul Henning Kirkegaard, Department of Engineering, Aarhus University.

The retina of the eye contains special photosensitive nerve cells called photoreceptors. They are connected to the brain and use the amount of blue and red light to determine the time of day. The researchers are trying to direct the manipulation of these nerve cells.

In connection with the study, the researchers installed special lighting that changes colour in the living room and bathroom at the nursing home, and set it to change both the frequency and the spectrum during the day.

Better balance between day and night
The researchers observed a better balance between day and night among the elderly residents at the nursing home, as well as more coherent sleep and fewer naps during the day.

They will now take a closer look at the effects of the coloured lighting, and hope to eventually be able to identify the optimal light mix with the right frequency content for elderly people.

“We’ve only just scratched the surface, but we’re lacking evidence-based knowledge about how the optimal circadian rhythm lighting should be composed for the elderly, as regards light intensity, colour composition and heat balance. We also lack knowledge about the role of the artificial circadian rhythm lighting combined with the coloured surroundings in the rooms in question, and particularly with the changing daylight,” says Professor Kirkegaard.

Elderly people’s circadian rhythm is a mess
Researchers estimate that at least 40% and right up to 70% of elderly people suffer from sleep disturbances, with a negative impact on a considerable number of cognitive and physical body functions.

“The circadian rhythm directs our cells to do something particular during the night and something else during the day. It’s a very fine balance, which regulates – to take just a couple of examples – metabolism, the nervous system, the immune system, blood pressure and heartbeat,” says Professor Kirkegaard.

The researchers consider it likely that they will be able to reduce the consumption of sleeping pills at nursing homes within a few years.

About the study

The researchers carried out the study of circadian rhythm lighting at the Fuglsangsø Nursing Home in Herning.

Eighteen elderly residents – thirteen female and five male – took part in the study for a period of three weeks.

The sleep behaviour of the elderly people was recorded using scores such as the Pittsburgh Sleep Quality Index (PSQI), which consists of nineteen different questions for assessing sleep quality.

The pilot study documents no clear correlation between lighting and sleep quality, but indicates a better day/night ratio for the people exposed to circadian rhythm lighting.

For more information, please contact

Professor Poul Henning Kirkegaard
Department of Engineering
Aarhus University

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