Impact of naturalistic lighting on hospitalized stroke patients in a rehabilitation unit: Design and measurement

ABSTRACT

Introduction and rationale: Stroke is a major cause of acquired cerebral disability among adults, frequently accompanied by depression, anxiety, cognitive impairment, disrupted sleep and fatigue. New ways of intervention to prevent these complications are therefore needed. The major circadian regulator, the suprachiasmatic nucleus, is mainly controlled by natural daylight, and the blue spectrum is considered the most powerful. During stroke rehabilitation, patients typically are mostly indoors and therefore not exposed to the natural daytime variation in light intensity. Furthermore, several rehabilitation hospitals may be exposed to powerful light in the blue spectrum, but at a time that is adversely related to their endogenous circadian phase, for example in the late evening instead of the daytime. Hypothesis: Naturalistic light that mimics the natural daytime spectrum variation will have a positive impact on the health of poststroke patients admitted to rehabilitation. We test specifically for improved sleep and less fatigue (questionnaires, polysomnography, Actiwatch), improved well-being (questionnaires), lessen anxiety and depression (questionnaires), improved cognition (tests), stabilizing of the autonomous nervous system (ECG/HR, blood pressure, temperature) and stabilizing of the diurnal biochemistry (blood markers). Study design: The study is a prospective parallel longitudinal randomized controlled study (quasi randomization). Stroke patients in need of rehabilitation will be included at the acute stroke unit and randomized to either the intervention unit (naturalistic lighting) or the control unit (CU) (standard lighting). The naturalistic light is installed in the entire IU (Cromaviso, Denmark). Conclusion: This study aims to elucidate the influence of naturalistic light on patients during long-term hospitalization in a real hospital setting. The hypotheses are based on preclinical research, as studies using naturalistic light have never been performed before. Investigating the effects of naturalistic light in a clinical setting is therefore much needed.

KEYWORDS:

• Anxiety
• circadian rhythm
• cognition
• depression, hospitalization. intervention
• light
• method description
• sleep
• stroke

Acknowledgments

We thank architect Maj Lis Brunsgård Seligmann and service manager Svend Morten Christiansson from the Service Center Rigshospitalet Glostrup for initiating the focus on the importance of indoor lighting and making it possible to install naturalistic light on an entire hospital ward. We thank engineer Torben Skov (ChromaViso) for the spectrum calculation and helpful discussions about illustration behind the light theory and the company ChromaViso for always being available for technical questions regarding the light setup.

Declaration of interest

The authors report no conflicts of interest. The biomedicine group has no economic interests in the company ChromaViso. ChromaViso delivered the light installation and had no influence on the study design and interpretation of the results.

Funding

This study has received research grant support from The Market Development Foundation, the Capital Region of Copenhagen and Service Center Rigshospitalet Glostrup and traveling grant from the University of Copenhagen.

Additional information

Funding

This study has received research grant support from The Market Development Foundation, the Capital Region of Copenhagen and Service Center Rigshospitalet Glostrup and traveling grant from the University of Copenhagen.