Do you leave lights on for your dog if you go out at night?

When we go out at night we usually leave the lights in our living room for our dog but when we go out in the afternoon we usually forget! Many times we had come home to a dark house and our dog is just so excited (or maybe more of relieved) to see that we have come home. Our dog sleeps alone in the dark every night so being left in the dark should not be a big issue although I personally think that it would be better to have a light on all the time especially when he is home alone. He is after all guarding our home so it would only be proper if he could see well. If you think normal light would be too costly leave a low watt light on