Other symptoms can include intolerance to cold, weight gain, dry skin, brittle hair, forgetfulness, problems with swallowing, voice changes, constipation, and increased menstrual flow. Another common cause of fatigue is sleep apnea. During sleep this condition causes episodes of a few seconds of breathing cessation. Sleep apnea decreases the level of oxygen in the blood and disrupts quality sleep. The National Sleep Foundation estimates that 18 million Americans may have sleep apnea.
Depression is another common cause of fatigue.
The American Psychiatric Association says that nearly one in ten Americans suffer from some degree of depression. Although effective treatments are available, many people either are not aware they are depressed or are too embarrassed to seek medical help. Fatigue can be a symptom of many other types of problems, such as job or family stress, allergies, rheumatoid arthritis, post-polio syndrome, or lupus. Excessive tiredness may also be associated with treatment and recovery from major medical events, such as surgery, stroke, or cancer. Since so many different problems can cause fatigue, it can take some detective work on the part of the physician and patient to find the cause and offer suitable treatment.