Biological Effects of Light

DOLL is working with lighting which fosters well-being. The potential is enormous since investment costs are limited and side effects non-existing compared to using medications.

Especially in elder care and rehabilitation, as well as hospitals, the potential for working actively with lighting is great. The sense of a circadian rhythm is not regulated when residents and patients cannot spend much time outside, unlike people with a daily routine that have to spend time outside e.g. on their way to work.

With dynamic LED-lighting power, colour combination and colour temperature can be regulated to imitate the levels of natural light experienced during the day. Research shows that this can help support humans’ natural circadian rhythm and thus support a good night's sleep.

Light at day, dark at night

During the day we need to be exposed to heavy daylight to keep up our natural circadian rhythm. It does not always feel that way since our eyes adjust to the conditions, but the intensity of the outdoor light is high compared to the indoor lighting.

The intensity and variation in daylight between light/dark and blue/red play an important role in keeping a 24-hour circadian rhythm. A specific centre in the brain regulates the circadian rhythm and body temperature, and secretes hormones. Amongst others, the brain produces serotonin, also known as ‘the happy hormone’. If we do not get enough light we will produce less serotonin and research implies that this has an effect on seasonal affective disorder amongst others.

When we get enough light during the day, our circadian rhythm is regulated so we sleep better. On the other hand, during the night it has to be dark. When it is completely dark and we sleep well, we produce “the sleep hormone” melatonin. The production of melatonin is reduced if we do not get enough light. This means that darkness during the night is also very important to the sleep-wake cycle. Lack of sleep can have negative effects on the power of concentration and the body’s hormone system.

Intelligent solutions, intelligent investments

Health benefits from lighting and its ability to foster well-being among people is attracting much attention these days. The European Commission considers better lighting solutions to be one of the tools that can make a difference in keeping older generations in Europe fit and functional.    

Large investments will prospectively be made in new buildings and in energy restorations of hospitals, as well as elder homes and assisted living facilities. During this process it would be obvious to integrate lighting solutions into the plans at the same level as other elements in the building and restoration process. This can minimise costs of installation considerably and lead to better environments for residents of elder homes and assisted living facilities, and to better working environment for employees. 


Flemming Madsen
Chief Developer
+45 2612 2630

DOLL is supported by: