In-home light therapy for fatigue following traumatic brain injury: A pilot randomized controlled trial

This project aims to develop, implement and evaluate the efficacy of an in-home light therapy treatment for individuals experiencing post-traumatic brain injury (PTBIF) and post-stroke fatigue. The study will be a pilot randomized controlled trial evaluating the impact of in-home lighting on subjective fatigue, as well as daytime sleepiness, sleep quality, psychomotor vigilance, mood, activity levels and quality of life. The study will employ a crossover design and thus all participants will be exposed to both lighting conditions (the active light condition, consisting of bright predominantly short wavelength light) and a second lighting condition that constitutes a placebo condition. Each will be 8 weeks in duration. Primary and secondary outcome variables will be measured at four weekly intervals: baseline, midway and end of each intervention and one month follow up, resulting in a protocol of 5.5 months, with six assessment points. Multiple measures will be taken at each of the assessment points. There will be no wash-out period between conditions as the carrover effects of the light are considered to be negligible. The main mechanism through which the light therapy is proposed to work is through the direct alerting or claiming effect of light. These patients do not have substantial circadian misalignment and therefore the light is not intended to correct and maintain a circadian phase problem, which would then make a ‘carry-over’ effect relevant over several subsequent days. The direct effects of light on alertness are immediate. When the light is changed to be less alerting, or switch off, there is a ‘half-life’ of about ~2 hours during which the alerting effects are maintained (for a wake example, see Rahman et al., Sleep 2014; for a sleep example, see Chellappa et al., J Sleep Res 2013). This duration of response (several hours) is not sufficient to require a wash-out between conditions that last for weeks, or to prompt concerns about any carry-over effects, as any influence will be gone by wake time. The longitudinal nature of the study does not allow for formal tracking of patient compliance but we will be able to detect light exposure patterns through the wrist-borne activity monitor, including changes in light spectrum. Regarding dose, we will measure the light levels emitted by the lights in situ for both lighting conditions using a standard measurement approach in terms of distance and direction from the light sources. It is unrealistic and not standard practice to purport to measure actual ‘dose’ received (and even then, corneal exposure does not match retinal exposure): One can only describe the light environment in detail, which we will do, and therefore quantify the minimum and maximum corneal exposure in a space. Device Description: The HealthE Genesis lamp is a tunable and programmable LED lamp developed by the Lighting Science Group Corporation (LSGC). The primary function of the lamp is to deliver a biologically-optimised spectrum of light for every time of the day. It aims to promote alertness, energy and focus during the day and healthy and restful sleep in the evening. It does this by giving off a high concentration of blue-enriched light during waking hours and warmer temperature light during the evening. The HealthE Genesis Lamp has an accompanying iOS application from which you can regulate the spectrum setting of the light. The lamps also have onboard sensors to monitor local air quality. Method of use: The lamps can be powered by standard power source and configured using the Genesis App on iOS. Mode of action and application: These lamps will be used as a bedside lamp for participants in the research study, as well as being placed in rooms that do not have sufficient ceiling lighting. The lamps in the experimental condition of this study will be programmed so that they produce blue-enriched high-intensity white light with a high correlated colour temperature (CCT) of approximately 5000-6500K in the morning or ideally all day if they do not have access to daylight. In the evening, for as long as possible before bed, gradual dimming and blue-depletion of the light will occur. Thus, low CCT light will be used (less than 2700K). Lamps will also be utilised in the placebo condition, however these will be programmed to reflect normal lighting conditions, and will not change in colour temperature across the course of the day/evening. Device Description: Standard commercially available light bulbs will be used in this study. The lighting will involve blue-enriched high-intensity white light with a high correlated colour temperature (CCT) of approximately 5000- 6500K during the day. In the evening, gradual dimming and blue- depletion of the light will occur (less than 2700K). Light bulbs of this colour temperature have been chosen due to the positive effects found following blue light treatment in a traumatic brain injury population, which include reducing fatigue and daytime sleepiness (Sinclair, Ponsford, Taffe, Lockley, & Rajaratnam, 2014). Mode of action and application: Possible lighting options in each participant’s house will be assessed prior to the commencement of the study to enable researchers to install light bulbs and lamps in appropriate places. Light bulbs will also be chosen based on the type of roof fixtures an individual has in their home (eg. some may have screw in light bulbs or bayonet fittings). These may vary between participants so the exact light bulb and its specifications will vary across participants, as not all fixtures will allow the same light bulbs. However an endeavour will be made by researchers to ensure that between participants, the spectrum and intensity of lighting is as similar as possible, within the specifications detailed above. The light bulbs for the roof lighting will be sourced from a local hardware store, such as Bunnings, following an assessment of the lighting set up and fixtures within participants homes. An electrician will be responsible for fitting lighting in participants’ houses due to OHS considerations. However it should be noted that the intended lighting is standard commercially available light bulbs for the residential home. The tailored lighting will remain installed for the duration of the active light condition of the study. Participants' normal house lighting will be re-installed for the placebo condition of the study. Researchers will work with participants to establish the appropriate timing of these applications during the active light condition. Device Description: Philips Respironics has a range of commercially available Actiwatches. Several different actiwatch models may be used with participants in this study including the Actiwatch 2 Activity monitor, Actiwatch Spectrum PLUS and the Actiwatch Spectrum PRO. They will all produce identical activity data. The use of different models is largely due to the availability of different watches in our research lab. The Phillips Actiwatch is a small, wrist-worn actigraph that measures motion. It looks and feels like a wristwatch. Mode of action and application: Participants will be required to wear the Actiwatch on their non-dominant wrist for the duration of the study (day and night), including the 2-4 week baseline period. Internal memory and programming allows Actiwatch to keep data for long periods of time. The watches can also record periods of light. The Actiwatch will measure participants' sleep-wake schedule, activity levels and light exposure to determine any impact of the two light conditions. This device is only being used as a monitoring device and is not an investigational product in regard to this project.