I Suspect My Son-in-law Is Doing Drugs

I am completely naive when it comes to drugs and drug use. I have a son-in-law who I suspect is on drugs. Can you tell me what kind of drug causes someone to sleep all the time. He has been to a pawn shop and pawned all of his tools. My daughter's bank account is so negative and she can't understand what he is doing with the $. He stays up all night because he can't sleep, gets up and goes to work day after day and then he just crashes. He can sleep at the drop of a hat. The other day his wife sent him to the store for milk and he was gone for almost an hour. She thought something was wrong and she went to look for him and she spotted his car at a house and stopped and they refused to let her in. He finally came out and he said he was comforting a guy friend that he knew and just happened to run into him. So he went back to his place for awhile. She knew that the house had been known as a drug house. What are the symptoms of drug use? Sleeping? Staying awake? He goes up into his room @ 4:00 locks the door. Refuses to let her in and doesn't get up until the next day.
you suspect?dont take this the wrong way but there is a little denile going on here. sounds like a stimulant to me.try confronting him,this takes courage. if you have questions for me just let me know