Certain skincare practices are fact: Drink tons of water for clear skin, apply sunscreen daily for protection against the sun’s harmful rays (and wrinkles!) and exfoliate weekly for a healthy glow. But then there’s the advice we follow blindly because our friends, magazines and “beauty experts” swear by it.

We hit up famed NYC dermatologist Dr. Neal Schultz, host of DermTV.com and creator of BeautyRx by Dr. Schultz — who’s been in the business for over 30 years — for some real talk.

Myth No.1: Never sleep with makeup on

Before you beat yourself up for falling asleep in layers of contouring foundation that would make Kim Kardashian proud, Dr. Schultz says it’s not that big of a deal. “Think about it this way,” he explains, “what’s the difference between wearing makeup on your skin for the eight hours that you’re sleeping as opposed to the 12 hours that you wear it when you get up in the morning at 8 a.m.?”  There’s really not much of a difference he insists, especially if you sleep on your back. But for your pillow’s sake, don’t make this a habit.

Myth No. 2:  Shaving makes your hair thicker

Most women torture themselves with waxing appointments because they’re afraid that shaving causes hair to grow in thicker. “I assure you that it does not,” says Dr. Schultz. “A natural, uncut hair has a wispy tip that all new natural hairs have. But the thickness of the hair shaft below the tip is much larger,” he explains. “When you shave or cut that hair at the surface, in a few days the hair is going to grow, and when it does, the tip will be rectangular and coarser than the thin wispy tip that you originally had. But the hair shaft is exactly the same thickness as before.”  The bottom line: “Shaving is not causing those hairs to get any thicker,” he says. 

Myth No. 3:  It’s crucial to wash your face post-workout

Yes, you should still always shower or freshen up post-workout. But when it comes to skincare, the most important time to wash your face is right before you hit the gym or do sports. “When you perspire, you tend to wipe your skin, which means you rub in the dirt and the oils that were already there, and that aggravates acne,” says Dr. Schultz. His advice: Wash off the dirt before you exercise. “After you’ve perspired, you’ve only made water and salt, and water and salt are harmless on the skin,” he says.