Everyone's been there: maybe it's too much one-on-one time with the hair dryer and curling iron, or the cumulative effect of at-home hair dying attempts. Or, maybe it's environmental—winter's brash, drying winds and indoor heaters and summer's overdose of sun exposure can both deplete strands of moisture and shine. Whatever the cause, there's no need to fret—with a few thoughtfully designed formulas, tools and accessories, you can revive hair in a matter of days...or even overnight. Below, discover our favorite (and hardest working) haircare products around.