I've had some light-sensitivity issues for as long as a remember. So I always get glasses with transitions. On computer though I've always been using flux [0] since it came out. I know that now a lot of OSes are supporting some kind of night mode, but I really like how there are some different parameters you can adjust in flux. And it's free.

[0] https://justgetflux.com/

Just read https://justgetflux.com/privacy/ carefully.

  We receive and store any information you knowingly provide to us. For example, if you use our Software to search for your location, we may collect geolocation data (including, without limitation, city names and specific addresses you provide).
  We may choose to buy or sell assets. In these types of transactions, customer information is typically one of the business assets that would be transferred.

I've discovered, for my part, that wearing yellow glasses works even better than f.lux when I'm working in an environment where I can't control the ambient lighting.

I will always upvote a comment supporting f.lux given the chance to. Fantastic piece of software.

Also worth mentioning Twilight on Android.