Flicker vertigo ( also known as Flicker Illness and the Bucha Effect ) is a neurological condition which involves feelings of vertigo and nausea during exposure to flickering light sources. The troublesome flicker rate is normally in the range of 1 Hz to 30 Hz, As might be expected, the brighter the light, the stronger the effect.

It was first reported as a medical problem in the 1950s when it was found that helicopter pilots could become disorientated when looking upwards through slowly rotating rotor blades.

Other example flicker sources include :

• Strobe lighting
• Wind turbine shadows
• Flickering reflected sunlight
• Low refresh-rate electronic displays
• Flashing advertisement displays
• Flickering TV ads
• Emergency vehicle hazard lights
• Paparazzi flash photography

It's now well known that flickering lights can also trigger seizure episodes in people with Epilepsyplugin-autotooltip__plain plugin-autotooltip_bigEpilepsy

"Epilepsy is a chronic noncommunicable disease of the brain that affects around 50 million people worldwide. It is characterized by recurrent seizures, which are brief episodes of involuntary movement that may involve a part of the body (partial) or the entire body (generalized) and are sometimes accompanied by loss of consciousness and control of bowel or bladder function. Seizure episodes are a result of excessive electrical discharges in a group of brain cells. Different parts of ….

Flickering lights can be uncomfortable to look at and can induce seizures in observers with photosensitive epilepsy. However, the temporal characteristics contributing to these effects are not fully known.

Source : Vision Research, 138, 18-28

The mechanism of action of the condition, either with epilepsy or without, is unknown.

There are suggestions that the flicker rate may somehow be interfering with 'brain wave' rates which tend to have roughly similar frequencies,

Further info. : Wikipedia

For detailed technical info, see paper cited above Vision Research, 138, 18-28