You need rest to grow. Sleep and time away from the gym are essential to the process of repairing the muscle tissue you damage by lifting weights. No matter who you are, there’s no way around this fact. But how much rest you need is a question that’s dogged exercise scientists for years. Now a new study from Japan suggests that a 12-day deconditioning period, in which no training at all is done, can help resensitize anabolic signals within your muscles—signals that can become desensitized to weight training stimuli over time.

It makes sense: Just as you need two or three vacations a year from work, your body could likely use a vacation from the gym. But is it really necessary to enter a 12-day deconditioning period? And if so, how often?

How much time?

According to elite powerlifter and International Sports Sciences Association founder Fred Hatfield, Ph.D., there’s no amount of time of that can be prescribed for everyone. “Everybody responds differently to exercise and the lack of exercise,” says Hatfield. “It all depends on how hard you train, and the volume and intensity of the eccentric training—that’s where the real damage is done. Elite-level powerlifters and bodybuilders could take a week, 10 days, or even longer to fully recover.”

Pro bodybuilders, powerlifters, and strongmen have a preponderance of white muscle fibers—the fibers that trigger high-intensity actions—which are torn to shreds after intense training, necessitating a longer recovery period. But for the average gym rat, a little experimentation is required.

Try a deconditioning period of a week to 10 days after three months of hard training; if you come back to the gym weaker, you rested too long. If so, try waiting up to four months before entering a deconditioning period again, or shorten the period to five to seven days. You’ll know you’re getting the right amount of rest when you return to the gym and don’t feel any weaker. And once you time it just right, your muscles will respond with growth.