These bad boys are amazing and really do work! Head to truedark.com to learn more about these glasses but I'll give you a brief run-down.
Both Red & Yellow glasses basically reduce the amount of blue-light into your day to day as, too much blue light isn't great for us... again, by doing some research into this, you will learn more.
The Red Glasses are used before bed-time as they heavily reduce the amount of blue-light you intake and really do help with sleeping if you use them before bed.
The Yellow Glasses are used during the day, and basically reduce the blue-light during the daytime.
Again, further research will assist with these bad boys, but I highly recommend these!