Modern life can feel like a juggling act. You try to balance work with life’s other commitments — paying bills, taking care of your house or car and feeding yourself or your family. It’s no wonder that half of respondents to a 2020 National Sleep Foundation survey said they feel tired most days of the week.

Yes, busy lives can wipe us out. But what if you’re sleeping okay and you’re still dragging through the day, unable to muster the energy to do what you want (and need) to do?

To answer that question, it’s important to differentiate sleepiness from tiredness, says W. Christopher Winter, MD. He’s a sleep specialist and neurologist based in Charlottesville, Virginia, and the author of The Rested Child and The Sleep Solution.

“For some people, tired means sleepy,” he says. “Sleepy as in, I have to walk around when my boss talks or I will fall asleep in the meeting room. For other people, tiredness is not a sleepiness problem but an energy problem.”

Knowing the difference can help you pinpoint the cause and have a more productive conversation with your doctor.

The American Academy of Sleep Medicine recommends that adults get seven or more hours of sleep per night to function at their best. Assuming you’re hitting that quota, there are many possible reasons for your fatigue that have nothing to do with your bedtime. Here, we dive into seven common culprits.

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7 common causes of fatigue

If no amount of sleep seems to do the trick, these are the culprits you should look to for an explanation.

Sleep apnea

You may be in bed for those seven hours, but how well are you really sleeping? Sleep apnea is the No. 1 cause of fatigue after sufficient sleep, says Joshua Tal, PhD. He’s a New York City–based clinical psychologist who specializes in treating sleep problems.

Sleep apnea is a condition that causes airways to collapse during sleep. Episodes of reduced or paused breathing last at least 10 seconds. And these episodes can happen often during the night. Each time this happens, the person is forced to wake up to breathe again. These awakenings are so brief that the person may not even remember them.

“A lot of sleep apnea goes undiagnosed, but it’s very common,” Tal says. “If you tend to doze off after an hour in the car or while watching TV, get tested.” If it turns out that you do have the condition, a CPAP for sleep apnea is 100% effective, says Tal. What you need to know about sleep apnea.

Depression

Fatigue is a common symptom of depression, says Tal. With depression, your energy levels can drop off. You may also lose interest in things or activities you once enjoyed. And it can make everyday tasks seem like herculean efforts.

Depression is known to disrupt some people’s sleep. But if you’re sleeping well and still feeling down and lethargic overall, you may want to get an assessment, Tal says.

Tal adds that treatment with an antidepressant may help you regain your energy. (Here, we answered your top questions about treatment for depression.)

Low thyroid levels

The thyroid is a gland in the front of your neck that releases hormones to help your body regulate and use energy. It controls important functions such as how fast your heart beats and how your digestive system works. (Who knew such a small gland could have so much power?)

Without enough thyroid hormone, these natural functions can slow down. This condition is called hypothyroidism. And one of the most common symptoms is fatigue. Other symptoms can include constipation, weight gain and feeling weak or stiff. Talk to your doctor if you’re experiencing these symptoms.

Medication side effects

Fatigue is a side effect of many medications. If you’re feeling extra tired and don’t know why, it may be time to review your medications with your doctor, suggests Dr. Winter. They may be able to help you pinpoint possible offenders.

Solutions may involve trying a lower dosage, taking the medication at a different time of day or swapping it out altogether.

Common medications that may lead to fatigue include:

• Antihistamines (found in sleep aids and allergy medication)
• Antidepressants
• Blood pressure medications (such as beta blockers)
• Sedatives (including benzodiazepines such as lorazepam)
• Prescription pain medications (such as opioids)

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Medical conditions that make it hard for your body to fuel itself

When your body can’t get enough oxygen and essential nutrients, everyday tasks may become harder. This can translate to physical (and mental) fatigue.

Conditions that fall into this category include anemia, chronic obstructive pulmonary disorder (COPD) and diabetes.

• Anemia happens when your body doesn’t make enough red blood cells. Without them, your body doesn’t get enough of the oxygen it needs to make energy. A common cause of anemia is low iron levels. 
   
• COPD is similar in that your body can find it harder to get enough oxygen. Many people with COPD sometimes chalk up their shortness of breath to getting older. But COPD is a serious lung disease that can impact your quality of life.
   
• Diabetes has 2 main forms: type 1, an autoimmune disorder, and type 2, where your cells aren’t as sensitive to the hormone insulin as they once were. In both cases, your body can struggle to deliver sugar from the blood into your muscles and tissues.

Stress

There’s no doubt that stress can build up over time. Maybe the hits seem to keep coming. Or you’re constantly extending yourself. Either way, it can reach a point where you’re just plain worn out, says Tal.

It’s not a character flaw. It’s a real phenomenon. According to the Mayo Clinic, it’s called emotional exhaustion. This can lead to symptoms such as lack of motivation and irritability. And it can bring on physical issues, such as fatigue, headaches and muscle tension.

The more fatigued you are, the less productive you can be, says Tal. And that can compound the stress. Your job: Rethink your schedule and priorities so that you have some time for yourself. As Tal says, “It’s time to learn to say no to requests more often.”

Your diet

Low energy could have something to do with what you put on your plate.

Eating a wholesome diet focused on vegetables, whole grains, lean proteins and healthy fats can help keep your energy balanced throughout the day. How? These foods are good at keeping your blood sugar stable. Just think about how you feel when you eat a candy bar or cookie. You may get a jolt of energy, but it likely doesn’t last long.

A balanced plate can also ensure you’re getting enough energy-supporting nutrients, such as iron and vitamins D and B12, says Dr. Winter. Before you reach for supplements, talk to your health care provider. “Your doctor may order some bloodwork to check for levels of these nutrients,” he says. And they can help you find the supplement that’s right for you.

Other healthy habits to support your energy include:

• Eating enough (and consistently)
• Limiting alcohol to the recommended two drinks a day for men and one for women
• Drinking water throughout the day

It’s common to feel tired and burned out from time to time. But when you find yourself slogging through each day, know that something besides your busy schedule may be to blame.