Duration: 8 weeks

Team: Team of 4 -
2 Biomed Engineers,
1 Industrial Designer,
1 UX Designer

Tools: Axure, Photoshop, Sketch

Letlight is a smart lighting system, designed specifically for the needs of the ICU and BCU. It is controlled by a wireless system using a mobile application. Using a wireless circadian lighting system keeps complexity and occupied space in the room to a minimum. Wireless systems can be implemented, controlled, and managed using a mobile application. By making a few adjustments to a hospital room’s existing lighting system, one can easily turn it into a smart lighting system.

Sleep and Light in Hospitals

Sleep is an integral part of a patient’s recovery process, especially when in the ICU and BCU.Patients in critical care units, along with other hospitalized patients, are predisposed to severe fragmentation and disturbed sleep.While there are many contributing factors for sleep deprivation including illness, medications, and patient care activities, the effect of light can be attributed as a major factor.Patients in ICU and BCU do not receive enough light through hospital windows or the artificial lighting systems. Moreover, the light that the patient receives is monotonous and does not mimic the natural light and hence disrupts the circadian rhythm.

Currently, hospitals do not have a fluid and easy mechanism that can help to mimic the natural light in the patient rooms. Hospital lights are installed to serve the purpose of examination and vision and are not smart lights that can understand the patient’s or staff’s need. These lights are artificial with singular properties and deviates from the natural light.

Semi Structured Interviews

To understand the functioning of the ICU and the BCU units, its layout and the challenges faced by patients and caregiving staff, we visited and interviewed ICU and BCU nursing staff from Emory Midtown Hospital, Atlanta and Piedmont Atlanta Hospital. We also interviewed professionals who work closely with healthcare in the field of architecture, lighting (Philips Health Systems, Netherlands) and psychology. Working with this multidisciplinary team helped in understanding the core problem and in shaping up possible solutions.

Research shows that, the natural sunlight has different components that vary from sunrise to sunset in terms of hue, temperature, and the amount of each light. For example, morning lighting has more blue light, helping one wake up, while evening lighting contains low levels of blue light, helping one fall to sleep. Lack of the proper combination of light disrupts the circadian rhythm. What we gathered was that It is not just the presence of light that causes slee[ disruption but also the absence of the right type of light at the right time. Thus a cycled lighting systems that copy natural light were considered important. We also found it important to have in place an easy mechanism through which patients and staff can control such a lighting system.


The system acknowledges different types of users and provides functions based on the users, to ensure that the system is user friendly and is meaningful. Letlight allows staff to tailor the lighting system for each patient as per the unique patient needs. The simple user friendly system is capable of learning based on routines and geographical location, demanding minimum technical expertise from the staff.


The lights are controlled by a mobile application. Physicians can control and fine tune all the lighting systems, modifying them based on patient needs by using the application from anywhere in the hospital. Patients can control the ambiance lighting and reading lights through the application.This application will come preset with default settings for circadian lighting, but will be customizable to best fit the patient’s needs if necessary.Intense, sudden light is not comfortable for a patient residing in a dim room. To avoid the lights suddenly being turned on, the app will have a button for staff to press a little bit before entering the room. This will make the lights gradually become brighter, making for a more comfortable patient experience. Importance was given to ease of use by patients. The overall system consists of four components along with the application:


The Day/Night Simulator will mimic the natural day and night cycle. These tunable lights will produce a wide range of white light, and can be adjusted to a wake time and sleep time by the physician as per patient needs. Wake time and Sleep time settings will alter the amount of blue light emitted, in order to promote sleep.


The Ambiance LED lights around the edges of the room will help enhance the mood and visual experience, improving the patient’s sense of wellbeing by providing a wide range of colored light. Patients will be given a wide range of ambience presets (Eg: Afternoon, Mountain, Rainy Day, Summer Beach) to choose from.


Controllable reading lights with low blue light emissions allow for reading without impacting the patient’s sleep cycle. These lights can be adjusted with different brightness setups as well as at different angles in which light falls. This light is placed close to the patient bed.


Examination lights, which can be remotely activated, will assist in caregiving. Staff can notify these lights in advance during routine checkups. Once notified, the light will gradually increase its brightness within 5 minutes. This avoids sudden bursts of light that cause sleep interruptions during patient checkups.