There is a long list of things that get better with age: jeans, whiskey, and cheese, just to name a few. However, your body and physical capabilities don't have it quite so easy. We start to see some not-so-favorable changes in strength and muscle mass as we pass through our third decade, and things don't get any easier from there.

What's to blame? Testosterone. In fact, after age 30, most men begin to experience a gradual decline in the hormone. It can be just a little dip, or it can be a nosedive, depending on a wide range of factors—from body composition to stress level.

Testosterone boosters are a class of herbal supplements aimed at naturally increasing your testosterone levels. Usually, they contain micronutrients that men are commonly deficient in, such as zinc, and which have been connected in research to healthy testosterone levels. They also may contain adaptogens, which are a class of supplement that are thought to help the body adapt to stress, or ingredients which have been connected to improved sleep. Sleep restriction has been shown to reduce testosterone in healthy young men, and as Chris Lockwood, Ph.D., notes, disturbed sleep is a common symptom of low T-levels.[1]

Testosterone boosters can work by increasing testosterone within a normal range or by providing indirect hormone support. Either way, in the end, these supplements are meant to give all the benefits a healthy testosterone level can provide: faster recovery from exercise, bigger and stronger muscles, and increased libido, to name a few.