How do I update my 1970's tongue and groove medium dark walls?

Paint them an off white or even a white white. Just make sure you clean the wood first of all dust dirt or smoke that make have accumulated through the years. It will brighten your whole place immediately.

My mother in law painted hers and it went from dungeon dark to bright and beautiful. Clean them well, put a primer on (you can tint your primer close to the color you are painting with) Might take a couple of coats since you're starting out with a dark surface.

Yes I would pickle them either a white, pale gray or blue for a brighter, fresher look.... https://www.google.com/search?q=pictures+of+pickled+tongue+and+groove+walls&client=opera&hs=J3I&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwix9LbRypHVAhUBWmMKHb7rBJUQ7AkISA&biw=1366&bih=629 https://www.pinterest.com/pin/83035186850081915/

video... https://www.youtube.com/watch?v=nKt-OkS_4GA

Trudy Fagre - light sand them down prime and paint a bright color will make the room feel larger.

My mom had a very dark wood wall. I told her for the longest time it needed to be painted. She said It wouldn't look good. Surprise, surprise once it was painted she loved it. The wood also gave the wall a nice texture. Make sure to clean the wall, prime and then paint. You too will love it!