Flickering can be defined as: the perception of visual instability/unsteadiness caused by lighting variations in brightness

Research has shown that flickering has an adverse effect on human well-being and causes tearing and eye fatigue. Currently, two flicker parameters have been developed by the IES. “Flicker Percent” which is featured by relative measure of cyclic variation in light amplitude and “Flicker Index” which includes the percentage of flicker, the shape of the waveform and the work cycle, which refers to the percentage of time in a single cycle.

In addition to flickering, we distinguish a separate stroboscopic effect, also called SVM (Stroboscopic Visibility Meausure). The SVM is a method used to quantify the stroboscopic effect visibility in general illumination application. SVM is defined by  measuring  the visibility  threshold  of  light  waveforms  modulated  at  several  frequencies and uses Fourier analysis to convert the wavelength shape of the light intensity. The stroboscopic effect can cause an impression of slowness, stopping or even reversal of the direction of movement of an object, which can lead to various accidents. The frequency amplifying the unwanted stroboscopic effect is between 80 Hz and 2kHz. In addition, stroboscopic effects can cause epilepsy, loss of perception and headaches.

At the LED line® Light Research and Measurement Centre, in addition to working towards elimination of flickering, we conduct continuous research on the negative impact of undesirable phenomena in lighting which it can have on health. As a manufacturer of lighting, we educate end users on the health aspects of artificial lighting through information campaigns and training.

Scientific research has shown that a person should spend several hours a day in light of 4000 lux in order for the body to function properly. If we are exposed to insufficient amount of light we can experience a significant decrease in concentration and become tired and feel a sense of sleepiness. What’s more, a person may fall into depressive state in the longer absence of exposure to natural light.

Artificial lighting is also not neutral to humans. The colour of artificial light can affect the mood, level of concentration and psyche of a person. The colour of the light is expressed by the colour temperature in kelvins (K). It is commonly believed that white colour light with a warm tint (below 3300 kelvins) gives a sense of comfort and relaxation. The neutral colour (4000 kelvins) works well in offices as it boosts up our concentration. On the other hand, the colour temperature of approximately 6000 - 6500 kelvins is considered to be comparable to the daylight (on a cloudless day).

LED lighting: tailor-made colours

LED line® offers a wide range of lighting solutions out of which we can choose the right  color temperature to suit our needs. LED line® lamps offer a wide range of colour temperatures from 2700 to 6500K.

In turn, among theLED line® strips you can choose from among those with a color temperature of 2400K to 13000K. Particularly, MULTIWHITE™ strips are unique in their construction as these solutions offer various tints of white colour. You can set any tint from cold to warm (3200 - 7000 Kelvins).


A significant parameter which is often overlooked by less experienced investors is the quality of illumination emitted by a luminaire – unified glare rating. The lower the UGR, the higher the comfort of people working within the illumination range of the luminaire. It is obvious that the greater the comfort, the higher the productivity of the employees.

Converting the UGR impact into quantifiable numerical values would be extremely time-consuming, but already at this stage it is possible to answer the above question in the affirmative manner. Yes, high-performance lighting increases employees’ productivity. That is why it is worth choosing luminaires with a low glare rating for the professional illumination of offices.


The photobiological safety PN-EN 62471 norms outline the main four risk groups:

  • Exempt (no risk):        No photobiological hazard;
  • Group 1 (low risk):        No photobiological hazard under normal behavioral limitations;
  • Group 2 (moderate risk):    Does not pose a hazard due to aversion response to bright light or thermal discomfort;
  • Group 3 (high risk):        Hazardous even for momentary exposure. The use of light sources in general lighting is not allowed.

Over and above, the norms make mention of the actual risks caused by both, natural and artificial light. These are inter alia:

  • UV-radiation risks to the eye and skin
  • UV-A eye hazard
  • The eye threat caused by blue light
  • Infrared eye hazard (IR)
  • Thermal hazard of the skin
  •  Thermal hazard of the retina

When analysing the above hazards, it is becoming  obvious that any sources of light shall be purchased from trusted manufacturers only.