Question to the Department for Transport:

To ask Her Majesty's Government whether the (1) flash frequency, and (2) brightness, of bicycle lights is regulated; if so, how it is enforced; and what assessment they have made of the impact of such lights' frequency and brightness on people with photosensitive epilepsy.

Published research identifies that flashing lights at certain intensities have the potential to trigger seizures in those who suffer from photosensitive epilepsy. It also reports the likelihood of such effects to be low and the frequency range most likely to cause such a response is 5-30 flashes per second (5-30Hz).

As such, the Road Vehicles Lighting Regulations 1989 (as amended) permit flashing bicycle lamps only if they have a frequency of no greater than 4 Hz, and not so bright as to cause undue dazzle or discomfort to other road users.

Enforcement of road traffic law is generally an operational matter for individual Police Forces and their Officers can issue verbal warnings, fixed penalty notices or report riders for formal prosecution.