The adrenal glands (small glands located over the kidneys) release many different hormones necessary for various body functions. Two major hormones produced by the adrenal glands are adrenaline and cortisol. These are the stress hormones which work with other hormones also produced by the adrenals. Adrenal fatigue results when the adrenal glands cannot keep up with the body’s stress hormone requirement. 
Adrenal fatigue is caused by illness or lifestyle conditions such as poor diet, smoking, allergies, malnutrition, excess caffeine, inadequate sleep, IBS, and yeast overgrowth (Candida).
Adrenal fatigue symptoms may be misdiagnosed or confused with other conditions. If you notice several of the following symptoms, you are probably suffering from adrenal fatigue: low energy levels, mild depression, salt cravings, frequent sighing, allergies, muscle weakness, feeling lightheaded upon standing up, feeling sleepy or cloudy-headed in the late afternoon, not feeling fully awake several hours after awakening, and getting a ”second wind” at 11pm lasting until 1am.
When you are under constant stress, the adrenal glands are in constant production mode. There is no prescriptive cure, but certain lifestyle recommendations can restore good adrenal function.
So the first step to recovery is to eliminate stress from your life. Of course not all stress is under your control, such as a bullying boss or being stuck in traffic, but there are many effective stress-relieving modalities you can tap into. One of the best and proven strategies is laughter. Laughter yoga stimulates the parasympathetic nervous system; this is the bodily system that restores rest to the adrenal glands. Laughter Yoga can reduce stress levels by 75% or more in just one session.
Other effective coping mechanisms include relaxation breaks, exercise, meditation, music, yoga, journal writing and prayer.
Reference: http://www.home-remedies-and-natural-cures.com/adrenal-fatigue.html