Expert advice needed.. this is a tough one.. ?

I have a year old yellow lab. I crate him if I am going to be gone from the house for fewer than 4 hours but never longer and I don't understand crating a dog at night. Why would you get a dog to keep in the house if you didn't want a dog in the house? Mine has always had free roam when we are at home. He has constant water and doesn't have to go out until we get up at 6 and has been doing this since 4 months of age. Since you remove your dogs food and water at 7 p.m. he/she could really be thirsty or hungry.