Feeling Fatigued? Finding Possible Causes

Fatigue can be helpful. It can be a warning sign that you need to ease up after strenuous exercise. Or it can make you rest if you get sick. But more often, fatigue creates problems. It can be an overwhelming and lasting feeling of exhaustion that makes it hard to do everyday tasks.

“There are different aspects of fatigue. It’s generally agreed that the sensation of fatigue can involve difficulty in starting or continuing an activity,” says Dr. Vicky Whittemore, who is involved in NIH’s fatigue-related research programs. “It can involve the perception that the effort to perform an activity is more than should be needed.”

Fatigue itself is not a disease. Rather, it’s a symptom. It can be caused by viral infections, certain medications, unhealthy eating, cancer and its treatments, depression or anxiety, and more.

Because it has so many possible causes, it can be hard for doctors to diagnose the origins of someone’s fatigue. This can make it difficult to develop an effective treatment plan. But your doctor can help you figure out where to start.

Making lifestyle changes can provide some people with relief. But these changes may not be enough for everyone. Certain health conditions can contribute to exhaustion. Some are treatable, such as a vitamin or mineral deficiency. But not much is known about other causes of fatigue.

One cause of debilitating fatigue is a serious disease called myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). ME/CFS causes long-lasting, severe exhaustion, along with flu-like symptoms (called post-exertional malaise). People with ME/CFS may also have sleep problems, pain, or “brain fog.” Brain fog is when you have trouble thinking or concentrating. Physical or mental activity can make ME/CFS symptoms worse.

Researchers have not yet found an effective way to diagnose or treat ME/CFS. However, its symptoms overlap with those seen in people with Long COVID. Long COVID arises when COVID-19 symptoms last weeks or months after infection. Experts estimate that around 20% of individuals with Long COVID will also be diagnosed with ME/CFS.

These similarities create new opportunities for scientists to uncover the biology behind fatigue. So, NIH is bringing together researchers from different fields and is providing new funding to help scientists tackle the mysteries of these and other forms of fatigue.

“The study of Long COVID is bringing light to many issues that the ME/CFS community has been exploring for years,” Whittemore says. “I think this research will help us better understand fatigue and get at the underlying mechanisms.”

How Can I Feel Less Tired?

Healthy lifestyle changes may help you regain energy:

• Eat a healthy diet. Nutritious foods can give you the energy to do things you enjoy.
• Get physically active. Experts recommend healthy adults get at least 150 minutes of moderate physical activity a week. Those with ME/CFS or Long COVID should talk with their healthcare provider before exercising.
• Get enough sleep at night. Adults need at least seven or more hours of sleep each night.
• Quit smoking. Smoking is linked to many conditions that can drain your energy. You can get free help at 1-800-QUIT-NOW or smokefree.gov.
• Limit alcohol. Experts suggest no more than one drink per day for women and two for men.
• Talk to a healthcare provider if you’ve been tired for several weeks with no relief.