"Adrenal exhaustion," often referred to as "adrenal fatigue," is a term used to describe a collection of symptoms, including fatigue and body aches, that some believe are caused by the adrenal glands being overstressed by prolonged stress.

Aging is the gradual and irreversible process of decline in physiological function and structure that occurs with increasing age in all living organisms.

Autoimmune diseases are health conditions that happen when your immune system attacks your body instead of defending it.

Cardiovascular disease is a group of diseases affecting your heart and blood vessels. These diseases can affect one or many parts of your heart and/or blood vessels. A person may be symptomatic (physically experiencing the disease) or asymptomatic (not feeling anything at all).

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complicated disorder.

It causes extreme fatigue that lasts for at least six months. Symptoms worsen with physical or mental activity but don't fully improve with rest.

The cause of ME/CFS is unknown, although there are many theories. Experts believe it might be triggered by a combination of factors.

Depression is more than just feeling down or having a bad day. When a sad mood lasts for a long time and interferes with normal, everyday functioning, you may be depressed.

Examples of anxiety disorders include generalized anxiety disorder, social anxiety disorder (social phobia), specific phobias and separation anxiety disorder. You can have more than one anxiety disorder. Sometimes anxiety results from a medical condition that needs treatment.

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder characterized by chronic abdominal pain and altered bowel habits. It can be subclassified in different subtypes according to the main clinical manifestation: constipation, diarrhea, mixed, and unclassified.

Fibromyalgia is a long-term condition that involves widespread body pain. The pain happens along with fatigue. It also can involve issues with sleep, memory and mood. Researchers think that fibromyalgia affects the way the brain and spinal cord process painful and nonpainful signals. That increases your overall sensitivity to pain.

A hormonal imbalance happens when you have too much or too little of one or more hormones — your body’s chemical messengers. It’s a broad term that can represent many different hormone-related conditions.

Insulin resistance is a complex condition in which your body doesn’t respond as it should to insulin. Insulin is a hormone your pancreas makes that’s essential for regulating blood sugar levels. Several genetic and lifestyle factors can contribute to insulin resistance.

Postural orthostatic tachycardia syndrome (POTS) is a condition that causes a number of symptoms when you transition from lying down to standing up, such as a fast heart rate, dizziness and fatigue. While there’s no cure, several treatments and lifestyle changes can help manage the symptoms of POTS.

Thyroid disease is an umbrella term for conditions that affect how your thyroid functions. Hypothyroidism and hyperthyroidism are the two main types of thyroid disease. But they each have multiple possible causes. Thyroid diseases are treatable — usually with medication.

Weight gain is an increase in body weight. This can involve an increase in muscle mass, fat deposits, excess fluids such as water or other factors. Weight gain can be a symptom of a serious medical condition.