The following factors may contribute to fatigue in arthritis:
Active disease – If you have an inflammatory arthritis or autoimmune disease, inflammation in your joints and other tissues can cause fatigue. Chemicals called cytokines, which are found in inflamed tissues, are similar to chemicals released in viral illnesses such as colds and flu, and they can cause extreme fatigue. Anaemia sometimes occurs with inflammation, and this can also cause fatigue.
Long-term conditions – Diabetes and thyroid problems can cause fatigue.
Drug treatment – Some drugs used to treat arthritis-related pain may cause drowsiness, loss of concentration and light-headedness.
Pain – Pain is a major symptom of most types of arthritis and it can wear you down, especially if it’s constant.
Muscle weakness – Inactivity due to pain or joint problems can cause your muscles to become weak, which may contribute to fatigue because it’ll take more effort to make your joints work. When you’re less physically active you can become unfit, and this can also cause fatigue.
Overdoing it – Pain and difficulties with joints and muscles can make it more difficult for people with arthritis to do tasks they would previously have found easy. Often people will keep going even after they know they should stop (for example when doing a physically challenging activity such as gardening), which can cause exhaustion for hours or days afterwards. This is called ‘boom and bust’ behaviour.
Stress or anxiety – Your body’s natural reaction to deal with stress is to release a hormone called adrenaline, which prepares your body to deal with a crisis (your muscles, heart and lungs work harder and your mind becomes very alert). This adrenaline release usually only lasts until the crisis passes, but if the stress continues (for example because of constant pain or anxiety about the future) and your body carries on releasing adrenaline, it can cause physical and mental exhaustion.
Sleep disturbance – If your sleep is disturbed due to pain, anxiety or stress, it can cause fatigue. Too much sleep can also make you fatigued, particularly going back to sleep in the day.
Low mood or depression – Sometimes people with a long-term condition feel down and uncertain about the future. This can lead to low mood or perhaps depression, which reduce energy or cause the feeling of fatigue.
Poor diet or hunger – A poor diet or missing meals may result in a lack of energy.
It’s likely that no single factor causes fatigue but that several combine and interact with each other. The combination may be different for everybody and vary each time. For example, your fatigue might be driven by inflammation, which also causes pain and disturbed sleep, but at another time you might be fatigued largely because of stress from a family crisis, which means you overdo things as you deal with it and end up missing meals.