So recently, I was doing a project which involved me working with dark structures. Yes I could have used a plugin like FullBright or Nodus to make the enviroment brighter, but I found a simple setting that does the job well.

1) Exit out of MC (keeping the launcher open is fine)
2) Navigate to the .minecraft folder
3) Open "options.txt"
4) change gamma:1.0 to gamma:100.0
5) Restart MC