Chronic fatigue syndrome (CFS) is a complicated disorder characterized by extreme fatigue that lasts for at least six months and that can't be fully explained by an underlying medical condition. The fatigue worsens with physical or mental activity, but doesn't improve with rest.
Physical causes of tiredness
iron deficiency anaemia. underactive thyroid (hypothyroidism) sleep apnoea.
Call for an appointment with your doctor if your fatigue has persisted for two or more weeks despite making an effort to rest, reduce stress, choose a healthy diet and drink plenty of fluids.
There are three types of fatigue: transient, cumulative, and circadian: Transient fatigue is acute fatigue brought on by extreme sleep restriction or extended hours awake within 1 or 2 days.
There are no medical tests to measure fatigue. But a good way to describe fatigue is on a scale of 1 to 10. Where 1 means you don't feel tired at all and 10 means the worst tiredness you can imagine. Some may use a questionnaire to help them work out how it's affecting you.
Even a week of feeling more tired than usual is not uncommon. Yet most people can tell when their fatigue feels like something more serious. If that's the case, or your fatigue gets worse or lasts longer than a week or two, it's time to see your doctor.
Doctors might refer patients to see a specialist, like a neurologist, rheumatologist, or a sleep specialist, to check for other conditions that can cause similar symptoms. These specialists might find other conditions that could be treated.
Medical causes – unrelenting exhaustion may be a sign of an underlying illness, such as a thyroid disorder, heart disease or diabetes. Lifestyle-related causes – alcohol or drugs or lack of regular exercise can lead to feelings of fatigue. Workplace-related causes – workplace stress can lead to feelings of fatigue.