I suck my tongue especially at night how can i stop?

sucking ur tongue is not like sucking your thumb because when u suck ur thumb ur actually putting ur hand to ur mouth wheres as my toungue is already in my mouth and it happens subconsciously. It is causing me to have an open bite. i have already had braces and i have had a series of retainer back and forth because its so hard to stop. any suggestions anyone...i've heard of hypnosis i dont know if that works though