" on health grounds " --- means related to, or regarding health. The meaning here is , -- how does daylight saving time affect health ?

Well, "on the grounds of" something usually means "because of" something. It seems that they are looking into daylight savings time because of some health reason. I imagine it could be something to do with natural rhythms of the body? Although our minds can re-adjust to an hour more or less depending on the season, it is difficult for our bodies to do so because they rely on a natural rhythm that we cannot reason with. It would be easier with more context :)