Circadian lighting reduces fatigue

Circadian lighting reduces fatigue in apoplexy patients admitted to hospital for rehabilitation of more than 2 weeks’ duration.
Approximately every third patient suffers from severe fatigue and exhaustion when admitted for a coronary or cerebral haemorrhage (apoplexy/stroke). One year after the stroke, fatigue is a major discomfort in 50% of the patients. Fatigue among stroke patients is related to poor rehabilitation outcomes and reduced functional capacities. After admission, it is associated with general poor quality of life and health-related quality of life.

Since 2013, a Danish research project at National Hospital of Denmark’s Department of Neurology, the Apoplexy Unit (Apopleksienheden, Neurologisk Klinik, Rigshospitalet) has carried out a controlled clinical trial for the purposes of investigating whether circadian light will exert an impact on apoplexy patients admitted for rehabilitation, relative to a number of parameters, comprising fatigue, sleep, circadian rhythm markers, cognitive abilities, anxiety and depression.

The study shows that the circadian lighting counteracts or effectively treats fatigue resulting from stroke or a brain haemorrhage.

Anders West, Doctor

In collaboration with the light company, Chromaviso, the research group and Rigshospitalet Glostrup’s operations department have developed a circadian light designed for the purpose of maintaining the natural circadian rhythm by imitating the sun’s natural light over the day’s 24 hours and thus create the necessary composition of light changes and darkness over the 24 hours of the day.

Results of fatigue
The first study results show a significant reduction in depression. Now, the fatigue results are completed and were recently presented at the European Stroke Organisation Conference in Prague 2017.

In the future, the circadian lighting should be considered as a part of the treatment environment during a rehabilitation course over two weeks.

Anders West, Doctor

Here, it was submitted that patients admitted to the ward with circadian lighting experienced significantly less fatigue as compared with patients at the control ward. The patients’ degree of fatigue was measured at their admittance and when they were discharged after a minimum of 2 weeks’ admittance. The Epworth Sleepiness Scale (ESS), the Multidimensional Fatigue Inventory questionnaire and the Rested Statement and Visual Analogue Scale for Fatigue were applied.

”This study demonstrates that circadian lighting will counteract or efficiently treat fatigue occurred in connection with a coronary or cerebral haemorrhage (apoplexy/stroke). In the future, circadian lighting should be considered as an element in the treatment environment for rehabilitation procedures in excess of 2 weeks,” Anders West explains.

 Non-medical stimulation
So far, research has been unable to explain the fatigue experienced by apoplexy patients. The fatigue can probably be ascribed to the brain damage – not necessarily to the sleep deprivation experienced by most patients.

This study on circadian lighting is the first non-pharmacological randomised study with a control group to demonstrate an impact by a non-medical stimulus relative to fatigue in apoplexy patients.



Facts about the project
In 2013, Copenhagen University Hospital and Aarhus University Hospital started working together with the company Chromaviso on developing and documenting research-based circadian lighting. It is a cross-disciplinary, public-private cooperation with support from the Market Development Fund.

About the circadian lighting
The lighting solution of the research project is called Circadian Lighting and has been developed by the Danish health-technological company Chromaviso in cooperation with researchers and the clinical staff at Copenhagen University Hospital and Aarhus University Hospital. It is based on a combination of insight into clinical everyday life, knowledge about the effect of the light on people and competences within circadian rhythm products and technology.

The Circadian Lighting includes a light protocol that creates the natural and steady rhythm between light and dark during day and night in order to ensure a health-promoting physiological effect, the stable circadian rhythm and the right balance between sleep and waking state. Furthermore, Circadian Lighting includes situation-specific light settings for various activities and needs. A night light free from blue light means that everyone can move safely around and carry out various tasks without the circadian rhythm being affected.

Circadian lighting is an automatically controlled lighting that changes during the day, parallel to the natural lighting outside. It rises slowly as the sun in the morning, it is strongest in the middle of the day, and in the evening a warm night light starts without the blue colors that run all night at hallways and offices, while it is dark in the bedrooms.

About the research at Copenhagen University Hospital 
The research project studies the effect of circadian lighting on rehabilitation patients at the apoplexy unit, neurological clinic, Copenhagen University Hospital, with regard to:

  • Sleep
  • Fatigue
  • Circadian rhythm markers
  • Cognitive abilities
  • Depression

It is a randomized clinical study with 90 patients with intervention as well as control. The results will be published on an ongoing basis in 2017 as a PhD project by Doctor Anders West. The first result was published at the International Stroke Conference, in Houston, Texas, showing a significant effect with regard to reduction of depression. At the  European Stroke Organisation Conference in Prague, the next resuts was published and it showed a significant effect with regard to reduction of fatigue and a significant effect in the circadian rhythm markers as well.




  • Chromaviso (Industry), CEO Anders Kryger
  • Operations department, Copenhagen University Hospital (Operation), Head of Centre Morten Christiansson
  • Unit of clinical apoplexy research, neurological dep. Copenhagen University Hospital (Clinic), Clinical research professor, chief physician, Doctor Helle K. Iversen

Other collaborators:

  • Danish Center for Sleep Medicine (The Capital Region of Denmark), professor and chief physician, Doctor Poul Jennum
  • Clinical Biochemical Department (The Capital Region of Denmark), Chief physician, PhD Henriette Sennels
  • Radiological Department (The Capital Region of Denmark), chief physician Frauke Wolfram
  • Opthalmology Department (The Capital Region of Denmark), sensior researcher PhD Birgit Sander
  • Physical and Occupational Therapy Department (The Capital Region of Denmark), Nora Holmegaard Beckman


  • The Market Development Fund
  • The Capital Region of Denmark
  • All departments above from the Copenhagen University Hospital.

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