Biologically effective lighting for more relaxed flights


cabin lighting with high red excitation purity

Partners from research and industry are studying the principles of next-generation cabin lighting

Gradual transitions from day into night have become standard today on board of modern passenger aircraft. Bergische Universität Wuppertal, the Fraunhofer Institute for Building Physics IBP, Airbus, Diehl Aerospace and Osram joined forces in a project to study how this scenario of colors and brightness can be improved to enhance passenger well-being using new chronobiologically adapted light. The result: Chronobiologically adapted lighting based on light-emitting diodes (LED), particularly on long-distance, overnight flights, leads to a medically measurable improvement in sleep, enhances well-being and promotes higher alertness upon arrival.

The model aircraft cabin at the Diehl site in Nuremberg was equipped like a real plane for the trials. Over six days, 32 test subjects each experienced three, realistic, long-distance, overnight flights on board of the simulator.

Results of the flight tests

The use of activating LED-based lighting systems improves rest and comfort parameters for passengers on long-distance flights. Warm, white light at the beginning of an overnight flight contributes to relaxation, promotes melatonin production and a slower heart rate, and thus makes the entire flight more relaxing for passengers by ensuring better sleep. In contrast, cold, white light (high blue component) in the morning after a restful night helps passengers to be more alert upon reaching their destination by suppressing excretion of the sleep hormone melatonin. Among business people, for example, this is reported to lead to better performance at their first business meeting the morning after a flight, and among tourists to a more rested start to their holiday.

Regulating the body clock with light

Light is the primary stimulus for regulating the human body clock and can therefore influence how well we rest. During the flights, the lighting was adapted to the respective phases and times of the journey using LEDs and intelligent light management systems. In addition to light intensity, the color spectra were selected in accordance with the time of day to support the circadian rhythm. The psychological and physiological reactions of the test subjects, including tiredness, sleep quality, stress, well-being and alertness, were measured and analyzed in an aircraft for the first time using a variety of medical instruments. Self- and external assessments were conducted on the basis of questionnaires; ECG measurements were taken for each test subject to determine heart rate variability; saliva samples were collected to document levels of the sleep hormone melatonin and the stress hormone cortisol; and movement sensors were used on the test subjects.

Light as a synchronizer

Light controls key bodily functions, including the sleep/wake rhythm, body temperature and hormone production. The sleep hormone melatonin promotes sleep and the stress hormone cortisol supports alertness. When we are active outdoors, it is mainly natural light that helps to synchronize our body clock. On the contrary, if we spend too much time indoors in poor lighting, or if we travel through time zones, for example on a long-distance flight, our body clock gets off track. Intelligent lighting solutions therefore are designed to minimize jet lag in the future and help passengers to overcome it more quickly.


Circadian rhythm: A biological rhythm with a period of about 24 hours (Latin: circa = approximately; dies = day), such as the sleep/wake rhythm in humans. The most important zeitgeber or synchronizer for circadian rhythms is light (cf. Lichtwissen 19 – p. 42).

Biological effect of light on humans: Light is electromagnetic radiation in the wavelength range of 380 to 780 nanometers visible to the human eye. The human eye perceives light with three different sensory cell types, which react to different wavelengths. Apart from the cones for seeing color during the day, the rods help us to see in less intense light. However, they cannot distinguish color. A recently discovered, third sensory cell type is biologically active, controlling human circadian rhythm and wakefulness. These sensory cells react to the blue wavelength range in the region of 460 nanometers (cf. Lichtwissen 19 - p.16).

cabin lighting with high blue excitation purity

measurement of a female test subject


Bergische Universität Wuppertal BUW, a university centrally located in the state of North Rhine-Westphalia, offers a diverse range of programs. Interesting degree programs are based on the latest results of innovative, top-level research and many are of interdisciplinary design. BUW also offers internships in cooperation with external partners. Teaching and research further benefit from an active network of international partner universities and good relations with partners in industry.

The focus of research in the Methods of Industrial Psychology/Experimental Industrial Psychology lab, part of the Department of Work and Organizational Psychology (Professor Dr. Jarek Krajewski), includes fatigue detection and management, as well as biosignal processing. The use of light to psychophysiologically influence humans is one area of the lab’s research.


OSRAM of Munich, Germany is one of the two leading light manufacturers in the world. The company's portfolio covers the entire value chain from components – including lamps, opto semiconductors like light-emitting diodes (LED) – to electronic control gears as well as complete luminaires, light management systems and lighting solutions. OSRAM has around 39,000 employees worldwide and generated revenue of 5.4 billion Euros in fiscal year 2012 (ended September 30, 2012). More than 70 percent of its revenue comes from energy-efficient products. The company's business activities have been focusing on light – and hence on quality of life – for over 100 years. Additional information can be found in the internet at


Diehl Aerosystems, a division of Diehl Stiftung & Co. KG, consolidates all aviation activities in the Diehl Group. With its business units, Diehl Aerospace and Diehl Aircabin (both joint ventures with Thales), Diehl Comfort Modules and Diehl Service Modules, Diehl Aerosystems is a leading, first-tier, global supplier of avionics and aircraft cabin solutions. The division currently has a workforce of 3,500. Customers include major aircraft manufacturers, such as Airbus, Boeing, Eurocopter and Embraer, as well as commercial airlines and other operators of passenger and business aircraft.


The Fraunhofer Institute for Building Physics IBP focuses on research, development, testing, demonstration and consulting in the various fields of building physics. These include noise control and sound insulation in buildings, the optimization of auditorium acoustics and solutions for improving energy efficiency and optimizing lighting technology. Fraunhofer IBP’s work also covers issues of climate control and the indoor environment, hygiene and health protection, building material emissions, weatherproofing and protection against heat and moisture, preservation of building structures and the conservation of historic monuments. Through comprehensive lifecycle engineering, products, services and processes are analyzed for their potential economic, environmental, social and technical impact, in order to evaluate the sustainability, long-term optimization and promotion of innovation processes. Research into the fields of building chemistry, building biology and hygiene, as well as concrete technology round out the Institute’s range of building science services. The Kassel site supports traditional activities in the field of efficient energy use, and is a center for the development of industrial and building system components. For more information, go to


Airbus is the leading aircraft manufacturer with the most modern and comprehensive family of commercial aircraft for the entire capacity range from 100 to over 500 seats. Over 11,500 aircraft have been sold to more than 470 customers and operators worldwide, and 7,500 of these have been delivered since the company first entered the market in the early Seventies. Airbus is an EADS company.