I suffer from a TBI, mild seizures and migraine. Extremely photosensitive, I was not able to look at my laptop for more than 30 minutes at a time without experiencing vertigo. F.lux has enabled me to get back to work and use my laptop for hours at a time. In terms of colour, if I really need to see something when browsing - I simply disable it for a short while. Never leave reviews but this app has changed my life. Amazing!