context: Fatigue is often confused with tiredness. Tiredness happens to everyone. It's a feeling you expect after certain activities or at the end of the day. Usually, you know why you are tired and a good night's sleep solves the problem. Fatigue is a lack of energy throughout the day. It is an unusual or excessive whole-body tiredness not relieved by sleep. It can last just for a short time (a month or less) or stay around for longer (one to six months or longer). Fatigue can prevent you from functioning normally and gets in the way of things you enjoy or need to do. Cancer-related fatigue is one of the most common side effects of cancer and its treatment. It is not predictable by tumor type, treatment, or stage of illness. Usually, it comes on suddenly, does not result from activity or exertion, and is not relieved by rest or sleep. It may continue even after treatment is complete. The exact reason for cancer-related fatigue is unknown. It may be related to the disease itself or its treatments. The following cancer treatments are commonly associated with fatigue: Chemotherapy. Any chemotherapy drug may cause fatigue, but it may be a more common side effect of drugs such as vincristine and cisplatin. Patients often notice fatigue after several weeks of chemotherapy, but this varies among patients. Some patients feel fatigue for a few days, while others say the problem persists throughout the course of treatment and even after it is completed. Radiation therapy. Radiation therapy can cause fatigue that increases over time. This can occur no matter where the treatment site is. Fatigue usually lasts from three to four weeks after treatment stops but can continue three months to one year after the treatment is finished. Combination therapy. More than one cancer treatment at the same time or one after the other increases the chances of developing fatigue. Several other factors could contribute to fatigue, including: Tumor cells compete for nutrients, often at the expense of the normal cells' growth. Decreased nutrition from the side effects of treatments (such as nausea, vomiting, mouth sores, taste changes, heartburn, or diarrhea) can also cause fatigue. Cancer treatments, specifically chemotherapy, can cause reduced blood counts, which may lead to anemia, a blood disorder that occurs when the blood cannot adequately transport oxygen through the body. When tissues don't get enough oxygen, fatigue can result. Medicines used to treat side effects such as nausea, pain, depression, anxiety, and seizures can also cause fatigue. Research shows that chronic, severe pain increases fatigue. Stress can worsen feelings of fatigue. Stress can result from dealing with the disease and the "unknowns," as well as from worrying about daily tasks or trying to meet others' needs. Fatigue may result when you try to maintain your normal daily routines and activities during treatments. Modifying your schedule and activities can help conserve energy. Depression and fatigue often go hand-in-hand. It may not be clear which started first. One way to sort this out is to try to understand your depressed feelings and how they affect your life. If you are depressed all the time, were depressed before your cancer diagnosis, or are preoccupied with feeling worthless and useless, you may need treatment for depression. The best way to combat fatigue is to treat the underlying medical cause. Unfortunately, the exact cause is often unknown, or there may be multiple causes. Some treatments may help improve fatigue caused by an underactive thyroid or anemia. Other causes of fatigue must be managed on an individual basis. You can use the following to help combat fatigue: Assessment. Evaluate your level of energy. Think of your personal energy stores as a "bank." Deposits and withdrawals have to be made over the course of the day or the week to balance the amount of energy you store and the amount you need each day. Keep a diary for one week to identify the time of day when you are either most fatigued or have the most energy. Note what you think may be contributing factors. Be alert to your personal warning signs of fatigue. These may include tired eyes, tired legs, whole-body tiredness, stiff shoulders, decreased energy or a lack of energy, inability to concentrate, weakness or malaise, boredom or lack of motivation, sleepiness, increased irritability, nervousness, anxiety, or impatience. Energy conservation. You can conserve your energy in several ways. Here are some suggestions: Plan ahead and organize your work. Change storage of items to reduce trips or reaching. Delegate tasks when needed. Combine activities and simplify details. Schedule rest. Balance periods of rest and work. Rest before you become fatigued. Frequent, short rests are more beneficial than one long nap. Pace yourself. A moderate pace is better than rushing through activities. Reduce sudden or prolonged straining. Alternate sitting and standing. Practice proper body mechanics. When sitting, use a chair with good back support. Sit up with your back straight and your shoulders back. Adjust the level of your work, Work without bending over. When bending to lift something, bend your knees and use your leg muscles to lift, not your back. Do not bend forward at the waist with your knees straight. Carry several small loads instead of one large one, or use a cart. Limit work that requires reaching over your head. Use long-handled tools. Store items lower. Delegate activities whenever possible. Limit work that increases muscle tension. Breathe evenly; do not hold your breath. Wear comfortable clothes to allow for free and easy breathing. Identify the effects of your environment. Avoid temperature extremes. Eliminate smoke or harmful fumes. Avoid long, hot showers or baths. Prioritize your activities. Decide what activities are important to you, and what could be delegated. Use your energy on important tasks. Other ways to combat fatigue include: Maintaining good nutrition; extra B vitamins seem to help lessen fatigue during radiation treatments. Getting moderate exercise on a regular basis Learning to manage stress Although cancer-related fatigue is a common, and often an expected side effect of cancer and its treatments, you should feel free to mention your concerns to your health care providers. Fatigue may be a clue to an underlying medical problem. Other times, there may be treatments to help control some of the causes of fatigue. Finally, there may be suggestions that are more specific to your situation that would help in combating your fatigue. Be sure to let your doctor or nurse know if you have: Increased shortness of breath with minimal exertion Uncontrolled pain Inability to control side effects from treatments (such as nausea, vomiting, diarrhea or loss of appetite) Uncontrollable anxiety or nervousness Ongoing depression