Knotty  girls could face a  brush  with disaster.  Hair maintenance is an all-too-important, albeit tricky form of self-care that, if mishandled, could leave folks with spilt ends,  warns a new, hair-raising report .  Rather than traumatizing one’s tresses with excessive heat — which causes hair to become brittle — followed by immediate brushing, researchers from the University of Dublin suggest treating freshly straightened strands to a 30-minute to two-hour recovery phase before styling.  Scientists suggest allowing one’s hair to rest for several hours after it’s been exposed to heat in order to prevent split-ends, according to a new study. WestLey/peopleimages.com – stock.adobe.com “Application of heat causes a dramatic reduction in performance…which is completely restored by a period of resting” study authors explained.…