Eva Longoria - actress, director and producer - revealed on the podcast "Project Swagger with Robin Arzón" that her sleep hours are sacred and that this is her biggest secret to feeling good inside and out. Almost every woman she talks to, she says, tells her she can survive on five hours of sleep. To her, that's one of the biggest beauty mistakes there is.

She mentioned shooting the Netflix comedy "The Fifth Wheel," which she directed herself, starring Kim Kardashian, Brenda Song and Nikki Glaser. The mostly female crew worked on a schedule that let mothers take their kids to school and put them to bed at night. When she's directing, Longoria gets up at five in the morning to work out before arriving on set - so she counts backward from her wake-up time to know when she has to go to bed.

Her evening routine is practically a military operation: magnesium supplements, eye masks, white-noise machines and a bedroom no warmer than 24 degrees. The trick she recommends most is simple - an alarm, but for going to bed, because it's easy to lose track of time. "Go to sleep. Ladies, go to bed," she says.

The science is on her side. Mireia Fernández, dermocosmetic director at the brand Perricone MD, explains that lack of sleep raises cortisol, the hormone that breaks down collagen and slows cell renewal. The effects show on the face: deeper expression lines, a weakened skin barrier and greater sensitivity.

Here's the part the podcasts leave out. The advice "get enough sleep" is free and correct - and yet the shelves are full of under-eye creams. Longoria has a crew, a schedule she sets herself and everything she needs for the perfect bedroom. A mother working two shifts, with kids and a six a.m. bus, doesn't count backward to bedtime - she counts how much is left until the day is over. When sleep becomes a beauty prescription, it's worth asking: who can actually afford it?