8 Reasons You're Tired All the Time

The combo of protein, healthy fat, and fiber provides lasting energy. So if you're not getting enough of these important nutrients throughout your day, your food may be zooming through you.

The fix: Aim for a mix of protein (from lean meat, eggs, and beans), healthy fat (from avocado, olives, and nuts), and carbs (from whole grains, vegetables, and fruit) at every meal.

"Pessimism is by definition exhausting," says Michelle Gielan, author of Broadcasting Happiness and founder of the Institute of Applied Positive Research. "Pessimists don't believe their behavior matters in the face of challenges, and that is a debilitating thought that can leave us stuck and unmotivated to take positive action." On the other hand, optimists expect positive things to happen in the face of setbacks and believe that taking action is necessary to success. "Just knowing there is potential for good things to happen fuels productive energy," says Gielan. One study confirms this: Optimistic sales professionals outsold their pessimistic counterparts by 37 percent, according to research at the University of Pennsylvania.

The fix: Get in the habit of creative problem solving—recognizing an optimistic belief and talking about solutions is energizing. "Simply listing a handful of things we are grateful for ahead of a workout or a project can put our brain in a more energized state," says Gielan.

Ever felt completely wiped, then ran a few miles or powered through a spin class and felt ready to conquer the world? Research shows there's something to this energy amp-up: When fatigued college students ran at a low intensity three times a week for six weeks, they felt less tired after six weeks, versus volunteers not instructed to exercise, found research in PLoS One.

The fix: Instead of giving into exhaustion-related relaxation (watching TV, shopping online, or reading) after dinner, consider a walk or exercise class.

Sugar equals energy, right? Nope. The sugar in a handful of jelly beans or a soda can cause a fast drop in blood sugar, taking a toll on your body and causing feelings of tiredness.

The fix: Aim to limit added sugars—such as granulated sugar, honey, maple syrup, agave nectar, and molasses—to no more than 10 percent of your daily calories, so about nine teaspoons of sugar for a 1,500-calorie diet. This rule will be easier to follow once the new food labeling guidelines are enforced in July 2018; at that point, added sugars will be a separate line item on nutrition labels. For now, watch out for sugar synonyms on ingredient lists. When you're baking, swap in a pinch or more of vanilla bean to reduce the sugar content in a recipe by up to 25 percent.

Feeling thirsty? That's a sign you're dehydrated, according to research in Nutrition Reviews. The slightest water loss can lead to fatigue, especially during exercise. Dehydration can also affect concentration and alertness: In a study in Physiology & Behavior, people who were mildly dehydrated and completed a two-hour simulated drive had significantly more driving errors, versus subjects who chugged enough water.

The fix: You've heard it a thousand times before but it's true. Drinking at least eight glasses of water a day is vital for your health. The National Academy of Sciences recommends 91 ounces daily for women (so, basically, a little over a half gallon), including water that comes from foods like fruits and veggies. Keep in mind you might need more water if you're exercising or under the weather. Increase sips by toting a sleek water bottle that you actually want to show off.

Now comes the difficult part to accomplish when your toddler refuses to go to sleep. Most people require 7 to 9 hours of sleep per night—and quality may be just as important as quantity. "Muscles rest and repair during the night, and the sleeping brain conducts multiple restorative functions during sleep such as calorie savings and removal of toxic waste from the brain," says Zlatan Krizan, PhD, associate professor of psychology at Iowa State University. Case in point: Volunteers who were woken up eight times per night over two consecutive evenings noticed a 31 percent drop in mood following the second night, compared to people who went to bed later but had no interruptions and saw only a 12 percent drop in mood, according to research in Sleep.

The fix: Set a regular bedtime, and conduct pre-sleep rituals to feel relaxed and ready to sleep—sip some tea, or read a few pages of a book. When you go to bed, make your sleep environment as noise-free and dark as possible: Don't keep your phone nearby (or at least mute the volume and turn it face down so the light isn't distracting), and close the blinds.

Allergies cause inflammation in the body, which leads to sleepiness and all of those other rather unfun symptoms like chronic sniffles. "Inflammation is due to an excess production of some chemicals that our body normally produces to fight infection and heal," says Erich P. Voigt, MD, division chief of general otolaryngology at New York University's Langone Medical Center. "When there is an excess or imbalance of these chemicals, the inflammation can make us feel ill. Also, swelling in the lungs may limit the body's ability to absorb oxygen and may also cause poor sleep quality, which then worsens the fatigue and can even lead to depressive symptoms."

The fix: Of course, it's impossible to avoid allergens like dust mites and pollen—so consider taking an allergy medication, such as over-the-counter Loratidine or Fexofenadine, before exposure happens, says Voigt.

Feeling exhausted is often a sign of iron deficiency. The mineral helps red blood cells transport oxygen throughout the body—and when that isn't happening efficiently, fatigue may set in. Women with heavy periods are particularly at risk for being low in iron.

The fix: Look to lean red meat and shellfish for animal-based iron, which your body best absorbs. Beans, leafy greens, and fortified cereal also offer iron, but pair these with foods rich in vitamin C (such as oranges) to increase absorption.