Nine years after she was diagnosed with idiopathic peripheral neuropathy, Barbara Montgomery, 70, says her condition has progressed and she has numbness, tingling, and aching in both feet every day—and sometimes stabbing pain. "My symptoms disrupt my sleep, waking me up repeatedly, making me feel tired and frustrated," says Montgomery, a part-time sales rep in Las Vegas. Between her disease and poor sleep, Montgomery is often too tired to clean her house, shop for groceries, or do other daily activities. She tries to pace herself and take it easy when she's very tired, but some days she doesn't have enough energy to do more than sit, she says.

Last year, Taylor Leddin started getting frequent migraines, usually in her left temple and often accompanied by nausea. "When they come on, all I can do is take medicine and sleep," says the 25-year-old public relations associate in Chicago, who also has fibromyalgia and depression. Sometimes, Leddin says, her migraine lasts 12 to 18 hours. "The next day I'm drained," she says. "I also feel sluggish and weak because I didn't eat enough due to the nausea." Fortunately, she has an understanding boss and the flexibility to work from home when she needs extra rest.

Fatigue is a common symptom of neurologic disorders. It affects one-third of people with multiple sclerosis (MS); prevalence is estimated at 28 to 58 percent of those with Parkinson's disease, and 36 to 77 percent of people who've had strokes, according to research published in a 2013 issue of Neurology. Among those with small fiber polyneuropathy, 98 percent report tiredness and 96 percent report reduced endurance or strength for activities, says Anne Louise Oaklander, MD, PhD, FAAN, associate professor of neurology at Massachusetts General Hospital and Harvard Medical School in Boston.

We don't fully understand all the mechanisms of fatigue, says Jason J. Sico, MD, FAAN, associate professor of neurology and internal medicine at the Yale School of Medicine in New Haven, CT. But changes in brain chemistry, particularly in levels of neurotransmitters such as serotonin, melatonin, and hypocretin (which regulates appetite and wakefulness), can affect mood and cognitive function and possibly contribute to fatigue. "In addition, the interconnectedness of pathways between higher cortical areas and the thalamus, basal ganglia, and limbic system are thought to be altered in patients experiencing fatigue," he says. "These alterations are likely a combination of the underlying neurologic disorder and how fatigue affects the brain."

Physical, mental, and emotional fatigue can play off each other, Dr. Sico says. After a stroke, for example, physical fatigue can stem from movement limitations, as well as vision and speech challenges. If you have weakness on one side, you'll need extra energy to do things like getting dressed, Dr. Sico says. "If you have speech difficulties and are unable to express yourself or be understood, you may feel mentally and emotionally drained." With mental fatigue, people may not have the energy to focus sufficiently on what they're reading or doing.

In specific neurologic conditions, fatigue may manifest differently. For instance, "people with MS often experience fatigue caused by damage to nerves that prevents them from transmitting electrical signals properly," explains Barbara S. Giesser, MD, FAAN, professor of neurology at the David Geffen UCLA School of Medicine and clinical director of the UCLA Multiple Sclerosis program. In addition, disruption of white matter connectivity (as seen on functional MRI scans) correlates with fatigue, says Lauren B. Krupp, MD, FAAN, professor of neurology and director of the Multiple Sclerosis Center at NYU Langone Medical Center. Another possible cause relates to immune changes, including low-grade systemic inflammation. "From a psychological point of view, if you feel like you're out of control because of MS, that probably adds to the experience of fatigue," explains Dr. Krupp.

With small fiber neuropathy, meanwhile, fatigue occurs partly because blood supply isn't keeping up with demand from muscles, says Dr. Oaklander. "When we exercise, the blood vessels in muscles dilate to boost local oxygen and energy, and constrict in places that are idle to compensate, a process that is regulated by small fiber nerve endings," she explains. "When the circulatory system loses neural control, as it does with neuropathy, the tissue—including possibly in the brain—fatigues prematurely."

Among people with epilepsy, fatigue may stem from sleep disruption due to nighttime seizures, daytime seizures that cause drowsiness in the postictal state (the altered state of consciousness after a seizure), anti-seizure medications, or depression, says Gregory D. Cascino, MD, FAAN, endowed professor of neuroscience at Mayo Clinic in Rochester, MN. "Approximately one-third of people with epilepsy have a mood disorder such as depression or anxiety. Fatigue is a common complaint among individuals with depression."

People with episodic migraine experience fatigue now and then. In a small study of 63 patients with chronic migraine, published in Neurological Sciences in 2016, 84 percent had severe fatigue, due partly to sleep disruption and anxiety or depressive symptoms.

Fatigue with neuromuscular disorders like myasthenia gravis and Guillain-Barre syndrome (GBS) may come from structural changes or altered metabolism in the muscle. Neuro-inflammatory disease (such as chronic inflammatory demyelinating polyneuropathy and GBS) may trigger a systemic inflammatory response that leads to fatigue, according to research in the journal Cellular and Molecular Life Sciences. With both types of disease, the prevalence of fatigue ranges from 38 to 86 percent, the study says.

Complicating Factors

Two distinct concepts-fatigue and fatigability-are often confused with each other, Dr. Krupp explains. Fatigue refers to a subjective feeling of weariness or exhaustion that's different from sleepiness and weakness. Fatigability reflects objective changes in performance over time, such as losing stamina while walking, losing strength with repeated muscle contractions, or losing cognitive efficiency or alertness with repeated cognitive effort.

Co-occurring conditions—such as thyroid dysfunction, low vitamin D or B12 levels, or anemia—also can contribute to fatigue, says Vijayshree Yadav, MD, FAAN, associate professor of neurology at the Oregon Health & Science University School of Medicine in Portland. The same is true of depression, anxiety, and other mood disorders.

Sleep disorders like insomnia, sleep apnea, and restless legs syndrome also are factors that may lead to fatigue for people with neurologic diseases, says neurologist Lynn Kataria, MD, chief of the sleep laboratory at the VA Medical Center in Washington, DC. "Restless legs syndrome and rapid eye movement sleep disorder [in which people act out their dreams] often occur with Parkinson's disease, and sleep apnea is common among people with MS, stroke, and headaches." Meanwhile, insomnia, which is so prevalent in chronic disorders, can affect almost anyone with a neurologic condition.

Medications typically prescribed for neurologic disorders can affect sleep. Those known to cause fatigue include topiramate for migraine and seizures; beta interferons for MS; benzodiazepines for anxiety, seizures, and insomnia; and certain antidepressants. Dr. Kataria notes that "many antiepileptic medications can cause either insomnia or hypersomnia [excessive sleepiness]." For a patient who experiences such a side effect, the doctor may be able to substitute a different medication, change the time of day it's taken, or reduce the dosage.

Because of the varied and large number of causes of fatigue, it cannot be erased with one easy fix. It may not decrease even if the contributing condition or neurologic disease itself is treated. "With Parkinson's disease, people who start out with fatigue tend to get more fatigue over time," says Joseph H. Friedman, MD, FAAN, director of the movement disorders program at Butler Hospital in Providence, RI. "It's very important for patients and their families to understand that fatigue is not a moral failing."

Patients can identify ways to cope with it, though. "Think about when you feel fatigue and the extent to which you feel out of control and why," Dr. Krupp advises. By listening to and observing your fatigue, she says, you can adjust your life and behavior to maximize your energy.

Essential Ways to Manage Fatigue

The key to reclaiming your energy is striking a balance between doing enough to alleviate fatigue and doing so much that you exacerbate it, says Jason J. Sico, MD, FAAN, associate professor of neurology and internal medicine at the Yale School of Medicine in New Haven, CT. Where that line falls varies from one person to the next, so it's important to find where it falls for you. Here are other strategies to ease fatigue.

Assess your medications. Fatigue and drowsiness are side effects of many drugs used to treat neurologic disorders and can also be caused by taking multiple medications. Your doctor may alter your medication or even prescribe medications off-label to reduce fatigue, says Barbara S. Giesser, MD, FAAN, professor of clinical neurology at the David Geffen UCLA School of Medicine. For example, modafinil (Provigil) and armodafinil (Nuvigil)—which are medications for narcolepsy—can help with MS-related fatigue, she says. Doctors may also prescribe stimulants such as amphetamine (Adderall) but would do so cautiously because of the potential for developing a tolerance to them, she adds.

Ease into exercise. "People with fatigue may not feel like exercising, but lack of physical activity can worsen fatigue," says Lynn Kataria, MD, chief of the sleep laboratory at the VA Medical Center in Washington, DC. Regular exercise improves cardiovascular function, circulation and oxygenation in different organs, and muscle strength. It also enhances mobility and cognition and triggers the release of natural endorphins that improve mood. Dr. Kataria recommends trying different kinds of exercise—walking, swimming, cycling, or yoga or tai chi classes—to find the type, intensity, and duration that help improve your fatigue rather than further drain your energy.

Practice mindfulness. In a review of three studies on mindfulness-based interventions, such as meditation, for multiple sclerosis (MS), published in a 2014 issue of BMC Neurology, researchers found that such techniques improved fatigue levels, as well as anxiety and depression. People with fatigue after stroke or traumatic brain injury may experience similar benefits from mindfulness training, according to a 2016 study in Frontiers in Psychology. "We're not sure whether it's because people are not expending energy unnecessarily or something else, but mindfulness enhances quality of life and lowers the experience of fatigue," says Lauren B. Krupp, MD, FAAN, professor of neurology and director of the Multiple Sclerosis Center at NYU Langone Medical Center.

Treat sleep disorders. If you know or suspect you have a sleep disorder, get it properly evaluated and treated, says Dr. Kataria. "I see sleep as low-hanging fruit—it's a relatively easy way to improve fatigue during the day," she says. For example, if you have sleep apnea, consider wearing a CPAP machine, which delivers continuous pressure to prevent the airway from collapsing during sleep. If you want to nap but worry that daytime dozing will disrupt your sleep-wake cycle, stick with a short snooze. A 10- to 20-minute catnap can ease fatigue without leaving you feeling groggy, says Dr. Kataria.

Use your time wisely. Organize your day to take advantage of your most energetic windows and conserve your resources at other times, advises Dr. Giesser. "Sometimes people with MS say they do pretty well in the morning and experience greater fatigue as the day goes on," she says. It makes sense, then, to do the most important things when you have the most energy, says Sarah F. Tyson, PhD, professor of rehabilitation at the University of Manchester in England. "Drop less crucial activities and rest frequently to recharge your batteries."

Be positive. The way you think about your health and your ability to deal with challenges can affect fatigue, for better or worse. In a study in a 2016 issue of the Journal of Behavioral Medicine, researchers examined how people with MS who were severely fatigued assessed social situations and their ability to manage them and found that those who had a positive view were better able to participate in activities and responsibilities at home, work, school, and socially. Staying positive helps Barbara Montgomery deal with peripheral neuropathy. "Thinking about what I'm grateful for keeps me from getting depressed, which protects my energy," she says.

Consider cognitive behavioral therapy. A course of cognitive behavioral therapy (CBT) "can do wonders for fatigue and even rewire the brain in a good way," Dr. Sico says. The therapy, which helps people change negative thoughts and feelings about their condition or symptoms, can improve patients' sense of control and ability to conserve energy, he says. "CBT can help you find your boundaries and learn how much you can push them." In a meta-analysis of 20 studies published in Frontiers in Neurology in 2018, researchers found that CBT decreased levels of fatigue among people with MS more than relaxation did.

Eat well. "A poor diet may contribute to fatigue," says Dr. Giesser. "If it contains lots of foods that are high on the glycemic index, it can cause blood sugar to soar and crash." To find out which eating patterns or particular foods could be fueling your fatigue, keep a food diary and note what you eat and when and how you feel a short while later, Dr. Sico advises. In MS-specific studies, following a very low-fat, plant-based diet had a significant positive impact on fatigue, according to research published in Multiple Sclerosis and Related Disorders in 2016. "[The participants] lost 20 pounds on average. That alone improved fatigue significantly," says Vijayshree Yadav, MD, FAAN, associate professor of neurology at the Oregon Health & Science University School of Medicine in Portland and the study's lead author.

Stay cool. It's important for MS patients to avoid getting overheated, Dr. Giesser says. "With MS, a demyelinated nerve will have trouble transmitting signals. If you heat up a nerve, its ability to conduct impulses is further impaired," she explains. "It's a temporary effect; it doesn't cause more nerve damage," she adds. To maintain proper body temperature, keep well hydrated; apply cold cloths to your face or try wearing cooling garments such as cold vests; don't go in hot tubs, saunas, or hot showers; and stay in air-conditioned places when it's hot outside.

Tend to your mood. In some instances, "fatigue can mask mood issues," Dr. Yadav says. "People who are depressed often complain of fatigue." If you're experiencing depression or anxiety, talk to your doctor about whether antidepressants or counseling could help, she advises.

Work with an occupational therapist. An occupational therapist (OT) will guide you in establishing routines at home, work, or school that simplify your life and conserve your energy, Dr. Yadav says. In addition, an OT can help you create systems to prevent you from misplacing or losing items if you also have cognitive fatigue or impairment.