Everyone feels worn-out some-times. These steps can help combat occasional fatigue: Try to stick to good sleeping habits. For example, limit naps to 30 minutes or less, and go to bed and get up at the same times every day. Limit caffeine and alcohol - especially in the evening. Snack frequently to keep your blood glucose level up. Choose grain-based snacks, such as graham crackers, pretzels, and fat-free rice cakes. Get regular physical activity. Exercise can increase energy and improve the quality of sleep. Talk to your doctor if you experience persistent fatigue for a month or longer. Many illnesses - including chronic fatigue syndrome, depression, and heart, lung and kidney problems - can cause excessive fatigue. So can certain medications.