The Purola Overnight Formula with Saw Palmetto is one of the most significant developments to date in the thinning hair and hair care field. It contains the EXACT formula developed by Dr. Purola in her studies conducted at the University of Helsinki in Finland which deep cleanses the hair follicles. The Purola Overnight Formula is easy to use – you just apply it nightly with the calibrated dropper directly to those areas of your scalp that need it most.