I'm a little confused by this research, if only because I thought it was common knowledge that much of the memory consolidation that occurs during sleep, occurs during REM and NonREM phase 2, which occur in cycles and so, are more possibly linked to certain levels of learning . . . . . . . . . . 

Laughter is regularly promoted as a source of health and well being, but it has been hard to pin down exactly why laughing feels so good. It is without a doubt one of the greatest mood lifters of all time. Perhaps God's greatest gift to mankind is a sense of humour!