In the study, employees reported improved sleep duration in colder and brighter lighting and in environments where light intensity and color temperature could be controlled.
Office workers first spend 3 weeks in a randomly selected lighting environment, and then stay in the new experimental environment for the next few weeks. The staff in the control group received standard office lighting with an average illuminance of 500 lux and neutral white light, while the team members received dynamic illumination of different color and intensity. These lamps are tailored to the age of the subjects.
Researchers measured light close to the eye and found that individuals in the personalized group showed higher levels of illumination in the morning and higher levels of color temperature near the table and eyes.
In the personalized group, the average sleep duration was reported to have been extended by 26 minutes.
To verify the results, the researchers will conduct further detailed analyses to control potential variables such as light sensitivity, general sleep quality and evaluation periods, and the actual illumination measured by the optical recorder.