What Justin Bieber, Zac Efron and Bradley Cooper have in common

It's hair!

Justin Bieber, Zac Efron and Bradley Cooperall have great heads of hair and have worn the kinds of styles women want to run their fingers through and men want to copy (at least in the cases of Efron and Cooper).

Men are influenced by the hair of popular celebrities -- even Mike "The Situation" Sorrentino of "Jersey Shore" has proved to be inspirational, writer Kavita Daswani found when she was researching a story for this Sunday's Image section about an increase in the numbers of men who dye their hair.Some are asking stylists for the same dark look Sorrentino sports; others just want to cover a little gray or add highlights.

In the same section, writer Chris Woolston looks into options formendealing withhair loss, and Jenn Harris takes us on a trip through time to look at male hairstyles through the ages.

But back to color.

Daswani found that when men go tostylists for color, they want to get the job done fast and discreetly. For men who'd rather touch up gray at home, she found a slew of products on the market, including:

- GetAwayGrey, a supplement containing the enzyme catalase, a lack of which can cause hair to whiten prematurely. Since the products launch a year ago, half of its customers have been men, ranging in age from ! 45 to 63 , a company spokesman said. ($29.99, Getawaygrey.com)

- The Gray Disappear wand from Generation Klean is for touching up stray gray strands on sideburns, beards and mustaches. It comes in four colors and washes out with shampoo. ($15.99, Generationklean.com)

- MiN New York makes an at-home kit based on its popular ProColor salon product. The kit contains enough dye for four applications. ($20 at MiN.com or at salons)

- Ambiance Volumizing Dry Shampoo comes in five colors with a thick, soft brush and is designed to cover up gray roots as the powder is delivered to the scalp. ($20.95 on Amazon.com)

- Redkens Color Camo, frequently used in salons, was most recommended by stylists for ease of use for those who want an at-home product. The five-minute color comes in a number of shades and can be customized to cover varying amounts of gray. (The home version costs around $12 and is available through numerous online retailers, including Amazon.)

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-- Susan Denley

Photos from left: Justin Beiber at the 39th American Music Awards; credit: Paul Buck / EPA. Zac Efron at the premiere of "New Year's Eve"; credit: Evan Agostini / Associated Press. Bradley Cooper in "Limitless"; credit: John Baer