Most household LED lighting use switch-mode power supplies and don't flicker. You don't need to use a fucking battery, just use a regulated power supply... ![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/facepalm.gif)
IIRC anything above 2kHz should be invisible/undetectable by a human, even including persistence of vision effects.
Nobody knows how brain processes information, but people used to use sun light and natural light sources, so even a few kHz light noise comming from modern LEDs might have some negative impact on how you feel.
When you didn't notice something moving very fast it doesn't mean that it has no impact on visual information processing in brain.
Another issue of moders LEDs is lack of IR radiation, which means that water wapour in air in a house rooms can't be heated, so nowadays people breathe with a bad quality air not energized by infrared radiation
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/facepalm.gif)
Of course most 230VAC home LEDs are flickering, but with higher noisy frequencies, while in the case of old light bulbs it was 100Hz flickering at 50Hz mains easy detectable by photoresistor, however those old more power needed bulb lamps had positive effect as a source of infrared light, which is esencial for human health, so modern "more" efficient LED lamps... leave people at homes with negative energy in the air