Dunkell provides some objective data about sleep and sleep disorders. but references are not provided. He analyzes body positions during sleep to explain human qualities and relationships. The approach Is neo-Freudian. Dunkell does not use standard symbolism for interpretation. His approach is subjective which can be impetus for gathering objective data, but none is referenced. I don’t think his interpretations can be applied to people who have severe physiological sleep disorders. He mentions this in the book, but emphasizes that sleep positions have deeper personal meanings. Freud may have once said "Sometimes, a cigar is just a cigar". Ditto for sleep positions!