That refers to the numbness many of us feel after sitting all day… say, because we’re at work, or we just streamed a full season of “Modern Family.” That can lead to what some people describe as “dead butt syndrome”… and health experts say it’s NOT a joke!

Because when you sit for a long period of time, your knees are bent and your hip muscles are flexed and often become shortened. This means your glutes, or butt muscles, involuntarily lengthen or relax… And if you sit that way every day, 8-hours a day, your butt muscles may become desensitized, because the neurons that tell them to contract have weakened. Meaning: They no longer KNOW how to activate, because they’ve been dormant for so long.

Dr. Chris Kolba is a physical therapist at the Ohio State University’s Medical Center… and he says “gluteal amnesia” could cause injury throughout the rest of your body if you don't take care of it. So, pay attention to symptoms like numbness, stiffness, or cramping in your glutes when you’re trying to exercise or just move in everyday life.

The good news is “dead butt syndrome” is totally reversible through exercises that work those muscles and bring them back to life. For example: Try side leg lifts, squats, and doing a “bridge” - where you lie on your back, plant your feet on the ground and raise your rear up and down. And of course, you should always make sure you’re moving throughout the day, to avoid health problems in the first place.