If you’re feeling overly tired or have little energy, you’re not alone.

Fatigue may be caused by simple factors like a lack of sleep or coming down with a cold or the flu. However, it can also be caused by underlying health conditions.

Even though everyone feels tired from time to time, chronic fatigue can harm your quality of life and prevent you from doing things you enjoy.

In most cases, fatigue can be remedied by lifestyle or dietary modifications, correcting a nutrient deficiency, or treating an underlying medical condition. Still, to improve fatigue, you need to get to the bottom of what’s causing it.

Here are 12 potential reasons why you’re always tired.

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Getting enough sleep is essential for overall health. Unfortunately, many of us don’t get enough, which may lead to fatigue.

During sleep, your body performs a number of critical processes, including releasing important growth hormones and repairing and regenerating cells. This is why most people wake up feeling refreshed, alert, and energized after a night of high quality sleep (1, 2, 3).

Importantly, sleep should be restful and uninterrupted to allow your brain to go through three stages of non-rapid eye movement (NREM) sleep and one stage of rapid eye movement (REM) sleep — the stage in which you dream (1).

Even though sleep time should be individualized, the American Academy of Sleep Medicine and Sleep Research Society recommends that adults get at least 7 hours of sleep per night for optimal health (2, 3).

Even though you may know the importance of getting enough sleep, falling and staying asleep can be a struggle.

Insomnia is a term for any condition that causes difficulty falling or staying asleep. It can be caused by several factors, including menopause, medical conditions, psychological stress, poor sleeping environments, and excessive mental stimulation (1, 4).

Insomnia is very common. In fact, one review noted that up to 40% of adults in the United States experience insomnia at some point in a given year (5).

Short-term insomnia, which lasts less than 3 months, is more common and affects 9.5% of the U.S. population. Yet, 1 in 5 cases of short-term insomnia turns into chronic insomnia, which occurs 3 or more times per week and lasts longer than 3 months (5).

If you’re experiencing insomnia, treatments like natural supplements, medications, and the management of underlying medical conditions may help. Visit your doctor to get the appropriate care and treatment.

Summary

Inadequate or poor quality sleep is a common cause of fatigue. Stress, medical conditions, and poor sleeping environments may negatively affect sleep and trigger insomnia. If you’re experiencing insomnia, consult your doctor for advice.

Nutrient deficiencies may lead you to feel exhausted on a daily basis, even if you’re getting more than 7 hours of sleep.

Deficiencies in the following nutrients have been linked to fatigue (6, 7):

  • iron
  • riboflavin (vitamin B2)
  • niacin (vitamin B3)
  • pantothenic acid (vitamin B5)
  • pyridoxine (vitamin B6)
  • folate (vitamin B9)
  • vitamin B12
  • vitamin D
  • vitamin C
  • magnesium

Deficiencies in many of these nutrients are quite common.

Anemia affects 25% of the world’s population. Iron deficiency anemia is the most common type, responsible for 50% of all anemia. Fatigue is one of the most common symptoms of this condition, but it typically improves once iron stores are restored (8).

Furthermore, studies suggest that up to 20% of people in the United States and United Kingdom ages 60 and over are deficient in vitamin B12. This deficiency is especially common in older adults because the body’s ability to absorb B12 declines with age (9).

B12 is critical for oxygen delivery and energy production, so low levels can cause extreme fatigue.

Additionally, a vitamin D deficiency may cause fatigue. Over half of the world’s population has inadequate vitamin D levels (10).

Because these deficiencies are quite common, it’s important to have your levels tested if you’re experiencing unexplained fatigue.

Typically, fatigue related to a deficiency in one or more nutrients improves once your nutrient levels normalize.

Summary

Deficiencies in certain nutrients — such as iron and vitamins B12 and D — may cause fatigue. Your doctor can test for nutrient deficiencies and suggest appropriate treatment.

Although some stress is normal, chronic stress is linked to fatigue (11, 12, 13).

In fact, chronic stress may lead to stress-related exhaustion disorder (ED), a medical condition characterized by psychological and physical symptoms of exhaustion (14).

Furthermore, chronic stress may cause structural and functional changes in your brain and lead to chronic inflammation, which may contribute to symptoms like fatigue (14, 15).

While you may be unable to avoid stressful situations, especially those related to work or family obligations, managing your stress may help prevent complete exhaustion.

For example, you can set aside time to decompress by taking a bath, meditating, or going for a walk (16).

A therapist may also help you develop strategies to reduce stress. Many health insurance plans cover mental health counseling, and virtual therapy is also an option.

Summary

Excessive stress may cause fatigue and reduce your quality of life. Prioritizing time for yourself and going to therapy may help you manage stress.

If you’re experiencing unexplained, chronic fatigue, you should visit your doctor and discuss your symptoms.

They may recommend testing to rule out certain health conditions that cause fatigue, such as sleep apnea, hypothyroidism, cancer, chronic fatigue syndrome, multiple sclerosis, anxiety disorders, kidney disease, depression, diabetes, and fibromyalgia (17, 18, 19).

It’s important to know that it’s abnormal to feel exhausted all the time. If you experience frequent fatigue, there’s likely one or more causes.

Getting proper treatment for an underlying medical condition can help you feel better and improve other areas of health as well.

Summary

Numerous medical conditions are linked to fatigue. If you’re chronically tired, it’s important to visit your healthcare professional to undergo appropriate testing.

Your diet significantly affects the way you feel.

To maintain energy and get the nutrients your body needs to perform critical processes, it’s important to consume a balanced diet high in nutrient-dense foods.

Undereating — or eating ultra-processed foods low in essential nutrients — may lead to calorie and nutrient deficiencies, which can cause exhaustion.

When you don’t obtain enough calories and nutrients like protein, your body starts breaking down fat and muscle to meet energy demands. This leads to a loss of body fat and muscle mass, which may trigger fatigue (20).

Older adults are especially at risk of malnutrition and nutrient deficiencies due to factors like age-related changes in appetite and reductions in physical activity (20).

Additionally, diets high in ultra-processed foods impair energy levels. For example, a diet high in added sugar may harm sleep and lead to chronically high blood sugar and insulin levels, which can result in fatigue (20).

In a 28-day study in 82 people, a diet high in refined sugars and highly processed grains resulted in 38% and 26% higher scores for depressive symptoms and fatigue, respectively, than a low glycemic load diet high in whole grains and legumes but low in added sugar (21).

What’s more, a review including over 53,000 postmenopausal women associated diets high in added sugars and refined grains with a greater risk of insomnia — and diets high in fruits, vegetables, and whole grains with a lower risk of insomnia (22).

Following a diet low in ultra-processed food and added sugar but rich in nutrient-dense foods like fruits, veggies, legumes, and protein sources like fish and eggs may help reduce fatigue and support healthy sleep while providing your body with optimal nutrition.

Summary

A diet high in ultra-processed foods may hamper your energy levels, so transitioning to a nutrient-dense diet loaded with whole, nourishing foods like fruits, vegetables, and legumes may reduce fatigue.

Although caffeinated beverages like coffee and energy drinks give you a temporary boost of energy, over-reliance on them may make you more tired the next day. That’s because too much caffeine can harm sleep, which may cause fatigue.

Research shows that feeling tired in the morning leads people to consume large amounts of caffeine, which impairs your sleep cycle. In turn, you may overuse coffee or other caffeinated drinks for energy, which continues the cycle of poor sleep followed by too much caffeine (23).

Drinking too much caffeine is linked to increased nighttime worrying, sleeplessness, increased nighttime awakenings, decreased total sleep time, and daytime sleepiness (24).

A study in 462 women linked high calorie coffee and energy drink intake to poor sleep quality and sleep disturbance. Those who didn’t drink these beverages reported better sleep quality (25).

Still, caffeine tolerance varies, and some people are more sensitive to caffeine’s effects on sleep than others (26).

While coffee and caffeinated beverages like green tea may benefit health when consumed in moderation, energy drinks are extremely high in stimulants and added sugar. Thus, you should avoid them whenever possible (27).

If you’re currently experiencing sleep issues and frequently drink caffeinated beverages, try cutting back to see whether it helps improve your sleep and energy levels.

Summary

Relying too heavily on caffeinated beverages may harm your sleep cycle and lead to fatigue. Therefore, cutting back on caffeine may help restore your sleep and energy levels.

Staying well hydrated is important for maintaining energy levels. The many biochemical reactions that take place in your body every day result in a loss of water that needs to be replaced.

Dehydration occurs when you don’t drink enough liquid to replace the water lost in your urine, stools, sweat, and breath. Several studies show that being dehydrated leads to lower energy levels and a decreased ability to concentrate (28, 29).

In fact, dehydration affects your entire body, including your sleep cycles.

A study in over 26,000 Chinese and American adults associated inadequate hydration with shorter sleep times (30).

Being dehydrated may also make you feel more fatigued during exercise and negatively affect exercise endurance (31).

Although you may have heard that you should drink eight, 8-ounce (240-mL) glasses of water daily, hydration needs depend on several factors, including your weight, age, sex, and activity levels.

The key is drinking enough to maintain good hydration. Common symptoms of dehydration include thirst, fatigue, dizziness, and headaches (28).

Summary

Even mild dehydration may reduce energy levels and alertness. Make sure to drink enough to replace fluids lost during the day.

Maintaining a healthy body weight is essential to overall health.

Not only is obesity significantly linked to a greater risk of many chronic illnesses like type 2 diabetes, heart disease, and certain cancers, but it may also increase your risk of chronic fatigue (32).

Obesity greatly increases your risk of obstructive sleep apnea, which is a common cause of daytime fatigue. It’s also linked to increased daytime sleepiness regardless of sleep apnea, suggesting that obesity directly affects the sleep cycle (33, 34, 35, 36).

What’s more, people with obesity have a higher risk of conditions associated with fatigue, including depression and type 2 diabetes (37, 38, 39).

Plus, poor sleep quality and sleep restriction may cause weight gain or obesity (40).

Maintaining a healthy body weight may support good sleep and energy levels, while getting high quality sleep may help prevent weight gain and reduce fatigue.

Summary

Obesity has been linked to poor sleep quality and conditions associated with fatigue like obstructive sleep apnea.

Many other conditions may lead to tiredness. It’s important to understand that several factors may be contributing to your exhaustion.

Here are a few other common reasons why you may feel tired:

  1. Drug and alcohol dependence. Research shows that people who are dependent on drugs or alcohol are more likely to experience fatigue (41).
  2. Shift work. Shift work causes sleep disruption and may result in fatigue. Sleep experts estimate that 2–5% of all shift workers have a sleep disorder characterized by excessive sleepiness or disrupted sleep over a period of 1 or more months (42, 43).
  3. A sedentary lifestyle. Leading a sedentary lifestyle may lead to tiredness during the day. Studies show that exercising more may improve symptoms of fatigue in some people, including those with medical conditions like multiple sclerosis (MS) (44, 45, 46).
  4. Certain medications. Some drugs, including steroids, blood pressure medications, and antidepressants, are linked to side effects like insomnia and increased tiredness (47, 48).

Help for drug or alcohol dependence

If you need help overcoming your addiction contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-HELP (4357).

It may be difficult or impossible to identify the factor(s) behind your fatigue on your own, which is why it’s important to work with a doctor you trust. They can help you find the cause and suggest possible treatments.

Summary

Medications, drug or alcohol dependence, a sedentary lifestyle, and shift work may all contribute to fatigue.

Even though everyone has days when they feel exhausted, constantly feeling run down and tired isn’t normal.

Many possible factors cause chronic fatigue, such as underlying medical conditions, nutrient deficiencies, sleep disturbances, caffeine intake, and chronic stress.

If you’re experiencing unexplained fatigue, it’s important to talk with your doctor to find the cause.

In many cases, your fatigue should improve once you identify the underlying cause(s) and make appropriate lifestyle and dietary adjustments — or get the right treatment for medical conditions.

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Just one thing

Try this today: When I started to feel extremely tired during the day, I knew that something was off. I ended up being diagnosed with Hashimoto’s disease after many months of visiting different doctors.

You know your body best and know when something isn’t right. If you’re feeling chronically exhausted even when you get adequate rest, there may be a medical condition contributing to your fatigue.

Work with a doctor you trust to get the right testing to rule out common health conditions that may be contributing to your fatigue.

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