Of more than 3,000 scientific studies that were found in a comprehensive search of 17 relevant databases, only about 4% had randomised controlled trials (RCTs), which are designed to exclude the placebo effect. Reviews of these RCTs consistently find that meditation without a focus on developing "mental silence", an aspect often excluded from techniques used in Western society, does not give better results than simply relaxing, listening to music or taking a short nap. While those who practiced mental silence showed clinically and statistically significant improvements in work related stress, depressed feelings, asthma-control, and quality of life as compared to commonly used stress management programs.
I was taught Transcendental Meditation in high school and learned some self-hypnosis techniques in college that I practiced a bit.
These types of meditation get you to focus/defocus your mind in active ways that appear to be beneficial.
If you're practicing some form of meditation that is just relaxing and daydreaming without trying to use your mind in a specific way - then it isn't really surprising that the results would be no different to relaxing and daydreaming or listening to music.