My first post was rubbish. See if this is any better. There are indications prayer and meditation are of benefit for emotional, spiritual, mental and physical health. Putting your mind into deep relaxation changes it physiologically like exercise changes the body. Like other health interventions some people are going to respond more than others, you need the right dose, there could be other aspects of your life reducing its effectiveness. If you exercise but also overeat you may not lose weight. It may take time to see results, some drugs used on the nervous system take weeks or months to show a response. Prayer is not a miracle cure it will give health benefits but they are likely to be more general than specific.
