Why am I always so tired? 5 common reasons for fatigue and how to improve your energy levels

Common reasons people may always feel tired include poor diet, dehydration, lack of sleep, and underlying medical conditions like a thyroid disorder.

• The most common reason people feel so tired is due to lack of sleep.
• Other causes of fatigue include a poor diet, stress, anxiety, and sleep disorders like sleep apnea.
• If you always feel tired, make sure to sleep 7-9 hours a night, drink water, and eat enough protein.
• Visit Insider's Health Reference library for more advice.

If you always feel tired, it may be sleepiness or fatigue - and there's a key difference. Sleepy people would sleep, given the opportunity, and it will often give them more energy. Fatigued people tend to have low energy levels regardless of sleep, and generally don't feel like doing much.

There are many causes of sleepiness and fatigue. Whether it's lack of sleep, poor sleep quality, a nutrient deficiency, or an underlying condition - here are some of the most common reasons why you may be feeling tired.

1. Make sure you're sleeping enough

If you find yourself feeling tired throughout the day, you should first assess whether you are getting enough sleep each night. According to the National Sleep Foundation, most adults should get seven to nine hours of sleep, while children need more depending on their age. Yet, an estimated one in three American adults don't get the recommended amount.

The quality of sleep is just as important as the number of hours, says Rajkumar Dasgupta, MD, assistant professor of clinical medicine at Keck School of Medicine at the University of Southern California. Sleep apnea, for example, can cause fragmented sleep, preventing you from getting into deeper, more restorative, sleep stages, which can lead to excessive sleepiness during the day.

If you think that lack of sleep, or low-quality sleep is the problem, then sticking to a routine may be helpful, says Stephanie Stahl, MD, a sleep medicine physician at Indiana University Health. Our bodies operate on internal clocks that regulate organ function, and maintaining regular cycles - by going to sleep and waking up at the same time - helps regulate this internal clock.

"If your sleep pattern is frequently changing, your body doesn't know when it's supposed to be awake or asleep and other body functions may be thrown off too," Stahl says.

This is especially important if you have an unusual schedule, like working a night shift. Studies have found that night shifts can be detrimental to overall health and increase your risk of cardiovascular disease. By sticking to the same schedule every day and limiting light exposure to create a dark, night-time environment, many shift workers can reset their internal clocks and adapt to their schedules, Stahl says.

2. Improve diet and nutrition

If you're not getting sufficient nutrients each day, or not drinking enough water, it may be part of the reason why you're always feeling tired.

You may need to rework certain parts of your diet to boost energy:

• Calories. Restricting your food intake to fewer than 1,000 calories a day can slow down your metabolic rate and lead to fatigue due to insufficient energy levels. The US Department of Health recommends adult males consume 2,000 to 3,000 calories a day and adult females consume 1,600 to 2,400 calories a day, depending on age and activity level.
• Protein. Without enough protein, the body can't build muscle as well. This can make simple acts like going for a walk more difficult, triggering fatigue. A 2017 study found that older adults who didn't consume adequate amounts of protein were almost twice as likely to have difficulty climbing steps or walking. The Recommended Dietary Allowance for protein (RDA) is 0.8 grams per kilogram of body weight, which translates to 55 grams a day for someone who weighs 150 pounds.
• Refined carbohydrates. Examples include white flour, white bread, pasta, white rice, and many breakfast cereals. These grains and sugars are lacking in nutrients and fiber for slow digestion. So, while snacking on refined carbohydrates might give you a temporary boost of energy, it'll leave you feeling burnt out later. Your body releases insulin to bring your blood sugar levels down when you eat refined carbohydrates. That release of insulin causes a sudden drop in blood sugar, which can make you feel tired.
• Dehydration. When you don't drink enough water, your body loses fluid, which decreases blood volume. This puts extra pressure on your heart to deliver oxygen and nutrients to your muscles and organs, which can lead to fatigue, says Ben Smarr, PhD, bioengineering and data science assistant professor at the University of California San Diego. The amount of water everyone needs each day varies by individual, but on average, men should be drinking 15.5 cups of water a day and women need 11.5 cups.

3. Exercise regularly

The level and type of physical activity each person needs to feel energized depends on many individual factors, Smarr says.

For example, one study found that low-intensity exercise, like walking, reduced symptoms of fatigue by 65% in sedentary people who regularly experience fatigue, and was even more effective than moderate exercise.

Smarr says a lack of physical activity can also leave you feeling tired, particularly after eating. This is when blood sugar spikes, and if you remain sedentary, those blood sugar levels remain high, which inhibits the body's ability to convert glucose from blood into cells for energy.

"Even the act of standing for a few minutes after your meal radically shortens the amount of time the blood sugar is in your blood," Smarr says.

Though you shouldn't necessarily engage in an intense workout after consuming a meal, moving around a little can help stabilize your blood sugar and reduce feelings of sluggishness associated with high blood sugar.

4. Check with your doctor about underlying medical conditions

These underlying medical conditions can cause you to feel tired:

• Chronic fatigue syndrome is characterized by extreme fatigue and sleepiness that interfere with daily life. This disorder affects women more than men and is more common at perimenopause when women in their 40's and 50's experience a decline in reproductive hormones.
• Pregnancy. Hormonal changes during pregnancy, particularly increased progesterone levels, can make you sleepy. Fatigue in pregnancy is most common during the first trimester, though some women experience it through the entire pregnancy.
• Anemia is a deficiency of red blood cells, or hemoglobin. Without enough hemoglobin in the blood, your muscles and organs don't get adequate levels of oxygen, which deprives them of energy and makes you feel fatigued.
• Sleep apnea is a sleep disorder that causes interruptions of breathing during sleep. People with sleep apnea wake often at night because they are struggling to breathe, leading to low quality sleep and daytime sleepiness.
• Thyroid problems. Both an underactive and overactive thyroid can affect sleep quality and contribute to feelings of fatigue, says David Cutler, MD, a family medicine physician at Providence Saint John's Health Center. Fatigue is a common symptom of an underactive thyroid, but an overactive thyroid can also increase your heart rate, making it difficult to sleep, Cutler says.
• Diabetes. Poorly controlled diabetes can affect sleep quality because if your blood sugar is high, you will need to urinate frequently, which can make it difficult to stay asleep, Cutler says. Fatigue is also a common symptom of high blood sugar levels.

5. Talk to an expert about your mental health

If it's not physical, it may be mental. Stress can disrupt sleep at night, which can cause daytime sleepiness, Dagupta says. Prolonged periods of stress can also contribute to fatigue and exhaustion.

Moreover, fatigue is a common symptom of depression, and both depression and anxiety can make it difficult to fall asleep at night, Dasgupta says. This cycle can perpetuate itself, as sleep deprivation can worsen depression and anxiety.

If you think your fatigue is associated with depression or anxiety, talk with your doctor. A health care provider can discuss medication options or help you make lifestyle changes to improve your sleep.

Insider's takeaway

More likely than not, the feeling of always being tired is due to a lack of quality of sleep. Therefore, make sure you are sleeping 7 to 9 hours a night and stick to a regular sleep schedule.

However, for some people, fatigue may be due to dehydration, consuming too many refined carbs, or stress. Or, it could be due to underlying health conditions like sleep apnea, anemia, or a thyroid disorder. So, if you find you're still tired after incorporating regular exercise, sleeping more, and following a healthy diet, reach out to your primary healthcare provider who can help you determine the cause.