Using Human Centric Lighting to Improve Inpatient Sleep: A Feasibility Study

BACKGROUND: Between 50-75% of hospitalized adults report disrupted sleep caused by environmental factors, such as staff interruptions, noise, and light exposure. These are known contributors to poor patient outcomes, including impaired immune response, elevated stress response, and increased sensitivity to pain. The impact of light exposure on sleep has been well established, as it directly impacts the circadian rhythm, or 24-hour sleep/wake cycle. Photoreceptors in the retina absorb light and stimulate the Suprachiasmic Nucleus (SCN), which acts as the pacemaker for circadian control. Light exposure, especially in the blue light range (460-500 nm) also influences melatonin production, which contributes to establishing healthy sleep patterns. Military patients may have even more circadian rhythm interruption than in civilian patients as they often have been transported through multiple time zones before admission.
Standard hospital lighting provides insufficient day-time light and too much night-time light, thereby impeding normal circadian rhythm function. In one study of 40 hospitalized medical patients, 35% of participants slept more than three hours during the day and 50% slept less than four hours during the night. Human Centric Lighting refers to lighting sources designed to mimic the natural light cycle in both brightness and light spectra. In controlled research settings and intensive care units, exposure to these light sources have been shown to improve sleep parameters and decrease negative outcomes. However, their effect on sleep and melatonin production in less controlled medical/surgical inpatient settings is not known, and the feasibility of conducting a randomized trial measuring these outcomes in a medical/surgical setting has not yet been determined.
SPECIFIC AIMS: 1. Assess the feasibility of screening, recruiting, and enrolling medical/surgical inpatients admitted to a control (standard lighting) and experimental (Human Centric Lighting) room in a medical/surgical setting. 2. Establish the feasibility of data collection resources for outcome measures of sleep parameters measured by the Consensus Sleep Diary and Actigraphy device (total sleep time and sleep efficiency), and salivary dim light melatonin onset. 3. Conduct a preliminary evaluation of participant responses to Human Centric Lighting in a medical/surgical setting.
DESIGN: A non-randomized pilot study will be used to assess the feasibility of recruitment and data collection processes, and assess preliminary responses to Human Centric Lighting in a medical/surgical setting. Descriptive qualitative and quantitative designs will be concurrently employed for this study.
METHOD: Two nearly identical medical/surgical rooms, with two beds each, will be designated as the study rooms. One room will have standard hospital lighting and the other room will be equipped with cycled lighting; bright white/blue light during the day time hours and a dimmable blue-light-depleted bulb for the evening and night time hours. To address Aims 1 and 2, qualitative data will be generated by the research team completing using a semi-structured interview and field notes completed weekly. To achieve Aim 3, participant response will be assessed by measuring and comparing total sleep time and sleep efficiency with both the Consensus Sleep Diary (CSD) and Actigraphy measures, sleep quality with the CSD, and by collecting salivary samples to measure dim light melatonin onset. Additionally, qualitative data will be collected through semi-structured interviews research team and participant interviews to determine if this intervention shows promise in the intended population (e.g., patients admitted to a medical surgical unit).
Results from this study will inform the design of multi-site fully-powered future studies using Human Centric Lighting interventions to improve outcomes for our military beneficiaries entrusted to our care. This safe and novel technology has possibility for broad application beyond the hospital setting, and could potentially be utilized in the homes and barracks of Warfighters, to enhance crew rest for flight crews, and in deployment settings to contribute to a fit and ready force.