Validation of a single forehead sensor against polysomnography and evaluation of the introduction of a circadian lighting solution on sleep, circadian rhythms and recovery in the intensive care unit (ICU)

We plan to consent and then recruit a feasibility sample of 30 patients to this study. All suitable patients will be approached to participate in the study and provide consent for the study evaluations. Consented patients will undergo objective sleep evaluation via formal sleep studies and validated questionnaires, and measurements of their circadian rhythms via blood tests and analysis of routinely collected physiological measurements such as core temperature, blood pressure and heart rate. All consenting patients will be assessed for delirium as part of routine patient screening in the ICU, and the data will be compared to evaluate whether there are any differences in sleep patterns / quality, circadian rhythms and recovery between delirious and non-delirious patients. A complete evaluation of the lighting conditions of the bedspace will be conducted, as well as measurements of sound and alarm levels. We will also evaluate patients’ self-reported quality of life, sleep and function 6 months after ICU discharge. The only intervention component of the study is the upgrade / rebuilding of two ICU bedspaces to improve the physical and sensory environments, including the installation of circadian lighting solutions. Study plan: 1. Sleep evaluation: Sleep evaluation will be performed in multiple ways. 1. Single forehead sensor electroencephalogram (EEG) 2. Polysomnography 3. Validated sleep questionnaires 1.1. Single forehead sensor EEG: Sleep will be measured continuously for the study period (for minimum of 2 days up to maximum 4 days (determined by whether they are still in ICU) following recruitment to the study) using a single forehead sensor EEG. This is a recently developed wearable device that is light and comfortable for patients to wear while enabling collection of high-quality EEG signals, and will be worn continuously for the duration of data collection (up to 4 days post-enrolment). The sensor will be administered by a trained university honours student supervised by a trained expert sleep scientist. 1.2. Polysomnography: Polysomnography (PSG) is the gold standard for sleep monitoring. Sleep will be concurrently measured using a portable Somtê polysomnography recorder for a 24-hour period between day 2 and 4 after recruitment to participate. The Somtê is a small, portable PSG that is worn as a belt across the patient’s thorax. Ten sensors are attached to the patient: 2 under the chin, 1 next to each eye, and 6 on the scalp. The sensors will measure and monitor muscle tone changes using electromyogram (EMG), eye movements using electroocculogram (EOG) and electrical activity in the brain using electroencephalogram (EEG). The EEG sensors will be attached to the patient’s skin using conductive electrode paste. The equipment also has an inbuilt oximeter to measure pulse oximetry and can also measure patient body position as well as background light and sound. The equipment also collects ECG, leg EMG, nasal pressure/thermistor and ribcage / abdominal movements. The PSG will be administered by a trained university honours student supervised by a trained expert sleep scientist. 1.3. Other / demographic data collection: Demographics and other relevant data will be collected and analysed against sleep quality/quantity as well as circadian rhythm disturbances (see below). 1.4. Sleep evaluation data and statistical analysis: Data collected via PSG and the single forehead sensor will be analysed in two ways. 1) The data will be analysed and interpreted by expert sleep scientists, which is the gold standard for sleep study interpretation. 2) The quality and quantity of sleep will also automatically be analysed and interpreted using the company automatic sleep staging algorithm. Manually analysed PSG data (gold standard) will be validated against manually analysed single forehead sensor data. Environmental noise and light, and nursing interventions, will be linked to sleep data where able to analyse reasons for disrupted sleep. Patients with delirium will be analysed and compared to patients without delirium. Delirium will be assessed twice daily during the study period using CAM-ICU (routinely collected in ICU). 2. Circadian rhythms: Data will be collected from environmental sensors, study records, participants, medical records and routinely collected biological samples. The following parameters will be analysed to evaluate the circadian synchronisation of the patients and study their influence on the outcome of the patients: 2.1. Continuous physiological data (routinely monitored): Body temperature, heart rate and heart rate variability, blood pressure, enteral feeding rhythm. 2.2. Sleep: As listed above. 2.3. Blood: 2 ml of blood will be collected from participating patients every 4 hours via their arterial line for a 24-hour study period. Cortisol, melatonin and IGF1 levels will be analysed, as well as untargeted RNA-sequencing and proteomics analysis, and lastly expression of circadian clock genes in white blood cells, which will allow the evaluation of the impact of the ICU environment on the global circadian rhythmicity of the patients. 3. Light quality and quantity: We are comparing 3 lighting environments available within a single ICU, with access to: • Room 1: Natural light and standard artificial light (standard window-facing bedspace) • Room 2: Standard artificial light (standard non-window facing bedspace) • Room 3: Novel artificial circadian light (redesigned non-window facing bedspace). The standard artificial light is a traditional ceiling light that is either on or off, controlled by the clinician, and no ability to vary or modify the intensity or colour temperature of the light. This will be controlled by the bedside clinician as per standard practice. The circadian lighting solution is a tuned and controlled light that will mimic natural daylight, with the intensity and colour temperature changing in a pre-set manner to imitate the outdoor lighting conditions. This will be fully automated, but the clinicians have the ability to over-ride the pre-programmed lighting should this be required for optimal clinical care. Patients will be admitted to an ICU bedspace (room type) as per standard unit admission and bedspace allocation, and suitable patients approached to participate in the study. A small number of participants may move between different types of bedspaces / room types depending on the clinical requirements and patient flow of the ICU at the time. We will follow-up the participants for the 4 day study period regardless of whether they move bedspaces or not.