Parisian women know a thing or two about beauty sleep. "Overnight treatment masks are very popular here," says Paris salon owner David Mallett. "To add moisture, many women will rub L'Occitane's shea butter cream on their scalp the evening before a shampoo." Another nighttime ritual: vitamins. "Women take herbal supplements to nourish their hair from the inside. Phyto Phytophanère ($25/bottle of 60 caplets; sephora.com) is an all-time favorite."