Why am I so tired? How to know if it’s your physical or mental health

First, are you tired, fatigued, or sleepy?

This might seem like semantics, but sleep experts say there’s actually a difference between these three words, and it might help you determine what’s behind your constant yawning.

Tiredness and fatigue are often used interchangeably, says Dr. Silverman. The difference is that tiredness is often used to explain a temporary state, while fatigue refers to a more persistent feeling of exhaustion that’s not always relieved by rest.

Fatigue can also include your whole body, says Tori-Lyn Mills, licensed clinical professional counselor at Thriveworks. “Your body can be heavy and you may feel sluggish,” she explains. Fatigue is a good way to describe that tired feeling that doesn’t fade as the day goes on, and you don’t ever seem to catch a second wind.

“Fatigue can be caused by hundreds of things,” Dr. Silverman adds. Some common examples include dehydration, boredom, chronic stress, anxiety, pain, and a long list of chronic conditions that can affect your energy levels.

Feeling sleepy is another important differentiator, Dr. Silverman says. “Sleepiness is when you can’t keep your eyes open, and you struggle to stay awake,” she explains, adding that it’s most often caused by sleep deprivation or insufficient sleep, like a bad night’s rest or a chronic sleep condition. “There is usually a clinical urgency to treat sleepiness because sleepiness is a safety issue,” as it’s more likely to impair you during the day and make things like driving unsafe.

6 sleep disorders that can make you tired all the time

It’s probably no surprise that sleep disorders are a major cause of daytime dragging. But they can do this in a few different ways: Some sleep disorders affect how much sleep you’re getting, others affect the quality of sleep you’re getting, and some sleep disorders keep you tired no matter how much sleep you’re getting.

Here are some sleep disorders to keep in mind if you’re always exhausted:

• Insomnia: Difficulty falling asleep, staying asleep, or getting back to sleep. Insomnia can be short-term or chronic, and it can happen on its own (primary insomnia) or as a result of another condition (secondary insomnia).
• Circadian rhythm disorders: A group of disorders that happen when a person’s internal body clock is out of sync with their environment.
• Sleep apnea: A condition that causes breathing to stop and start throughout the night, which can cause snoring and waking up gasping for air.
• Restless leg syndrome: A neurological condition that causes involuntary leg movements, particularly at night, which can make it difficult to fall or stay asleep.
• Narcolepsy: A neurological disorder that affects the brain’s sleep-wake cycles, causing excessive daytime sleepiness and fragmented sleep at night.
• Hypersomnia: A sleep disorder marked by excessive daytime sleepiness and regularly sleeping more than 11 hours a night, which is typically diagnosed after ruling out other causes.

Signs to look for:

• You’re falling asleep at random times during the day. You’re not just dragging—you’re actively fighting off sleep. This usually signals accumulated sleep debt or an underlying sleep disorder.
• You wake up feeling like you never slept, even after a full night. This is a clear sign your sleep isn’t restorative, which could be caused by many of the sleep conditions above.
• You crash at night but can’t fall asleep, or you wake up for long stretches in the middle of the night. Both of these are classic manifestations of insomnia, Dr. Silverman says. In some cases, middle-of-the-night wakes can also point to untreated sleep apnea, she adds: “If someone is waking up gasping or choking, or in a state of panic, their brain may be on high alert and keep them awake for long periods of time.”
• This isn’t an occasional thing—it’s been going on for a few months. Dr. Silverman says that experts typically suspect a sleep disorder if sleep issues persist for three months or longer.

When to talk to a provider—and who to see:

If you suspect you might have a sleep disorder and have symptoms lasting for months, it’s best to check in with a sleep specialist. “I think it’s really important to advocate for a sleep evaluation and a referral to a sleep specialist if you’re feeling so tired, fatigued, or sleepy during the day that it is truly interfering with your ability to function on a regular basis,” Dr. Silverman says.

She suggests starting with a medical provider you trust, like your primary care provider. They can refer you to a sleep specialist and may also run some labs to check for any underlying health conditions or deficiencies that may be contributing.

If you’re struggling with insomnia or find yourself dreading bedtime after too many stressful nights of too-little sleep, consider checking in with a therapist, too. Cognitive behavioral therapy (CBT) can help you reframe your thoughts around sleep, making it less anxiety-inducing. Cognitive behavioral therapy for insomnia (CBT-I) is considered the gold standard for treating the condition.

How to know if there’s a medical issue behind your exhaustion

The frustrating truth is that so many health conditions can come with a side of fatigue, which is why it’s worth getting a check-up if you’ve been dragging for a while without any clear explanation.

“Vitamin and mineral deficiencies, as well as chronic health conditions, can certainly be potential root causes of physical exhaustion and fatigue,” Dr. Silverman says. “I think it’s important to get your blood work done at least once a year, but ideally every three to six months if you’re tired all the time.”

Common medical causes to be aware of:

• Nutrient deficiencies: Low iron (especially ferritin), vitamin D deficiency, and B-vitamin deficiencies (particularly B12 and folate) are among the most frequent culprits.
• Thyroid issues: Hypothyroidism (an underactive thyroid) is a classic cause of persistent fatigue and is often underdiagnosed, especially in women.
• Blood sugar imbalances: Both diabetes and irregular blood sugar levels can sap your energy.
• Hormonal changes: Perimenopause and menopause can significantly disrupt sleep through hormonal fluctuations, night sweats, and an increased risk of sleep apnea—which, Dr. Silverman notes, is “often completely overlooked and misdiagnosed in women.”
• Chronic conditions: Cardiovascular disease, autoimmune conditions (like lupus, inflammatory bowel disease, and multiple sclerosis), and cancer can all affect energy levels.
  Infections: Hepatitis, mononucleosis, and long COVID are among the infections known to cause lingering fatigue.
• ME/CFS: Myalgic encephalomyelitis/chronic fatigue syndrome is a condition defined by substantial, persistent fatigue lasting more than six months that isn’t caused by exertion, isn’t relieved by rest, and gets worse after activity (physical, mental, or emotional). There’s no single diagnostic test, but doctors can diagnose it using established clinical criteria. If this sounds familiar, it’s worth bringing up with your doctor.

When to talk to a provider—and who to see:

Start with your primary care doctor. It’s helpful to come prepared with the following details:

• How long it’s been going on
• When it’s most severe
• Whether or not rest helps
• Any other symptoms you’ve noticed (mood changes, weight fluctuations, feeling cold, brain fog, etc.).

From there, your doctor will likely order some bloodwork to check for deficiencies and screen for common conditions. Depending on the results, you may be referred to a specialist (like an endocrinologist for thyroid or hormone issues, a rheumatologist for autoimmune concerns, or a sleep specialist if there’s reason to think a sleep disorder is involved).

How to know if it’s actually emotional exhaustion

That constant dragging feeling may actually have to do with your mental health. And that doesn’t mean that exhaustion is “all in your head”—just that fatigue is a very real byproduct of stress, burnout, and overwhelm.

Emotional fatigue can also feed directly into sleep problems, creating a hard-to-fix loop where stress ruins your sleep, poor sleep makes everything feel more overwhelming, and stressing about your lack of rest makes restorative sleep even more elusive.

Sleep struggles—like not being able to sleep or feeling like you could sleep forever—can also be a symptom of a mental health condition like depression, anxiety, or PTSD. ADHD can also make you feel exhausted, says Mills, “especially if you feel overwhelmed, underestimated, or like your brain is having to work overtime.”

Signs to look for:

• Your tiredness feels more emotional than physical—like an all-consuming lack of motivation where everyday tasks feel insurmountable. Going to the grocery store feels like running a 5K.
• You can’t fall asleep because your mind won’t stop, even though you’re exhausted.
• You’re constantly overbooking yourself or never fully switching off. Basically, it’s not a secret that you’re stressed.
• You’re also experiencing other mental health symptoms, like irritability, anxiety, loss of interest, or trouble focusing.

When to talk to a provider—and who to see:

If emotional exhaustion feels like your baseline rather than your response to an especially rough week, it’s worth talking to a mental health provider. They’ll likely ask you about your sleep, mood, and stress levels, as well as any other mental health symptoms you might be experiencing. From there, they can help you identify factors contributing to your chronic stress and burnout, give you tools to manage stress and feelings of overwhelm, and help you find ways to reduce your mental and emotional load when you can’t immediately change the situation.

If you’re not sure where to start, your primary care provider can help point you in the right direction and rule out any overlapping physical causes.

Frequently asked questions (FAQs)

What is the difference between tiredness and fatigue?

Tiredness and fatigue are often used interchangeably. The main difference is that tiredness is often used to explain something temporary, while fatigue refers to a persistent, almost pervasive, feeling of exhaustion that doesn’t seem to go away even if you prioritize rest.

Can anxiety or depression make you feel tired all the time?

Both anxiety and depression can cause fatigue and leave you feeling constantly tired. Stress and worry can be emotionally draining, and both mental health conditions can cause insomnia or other issues with sleep.

What deficiencies cause tiredness?

The most common nutrient deficiencies that cause tiredness are iron (especially low ferritin), vitamin D, and B vitamins, especially B12 and folate.

When should I see a doctor about being tired all the time?

If your tiredness interferes with your ability to function during the day, or if it’s happening on a regular basis, it’s a good idea to see a doctor to get to the bottom of why you don’t have enough energy.

Can being too sedentary make you more tired?

Yes, being too sedentary can cause your body to produce less energy, slow circulation, and reduce the alertness-inducing chemicals in your brain, leaving you feeling tired and unmotivated. Even light movement, such as walking or stretching, can jumpstart energy levels and reduce fatigue.

Why am I tired even after a full night of sleep?

Waking up feeling tired after a full night of sleep is often a sign of poor sleep quality. This can point to an underlying sleep disorder, such as sleep apnea, restless leg syndrome, or a circadian rhythm disorder, which can cause sleep to be low quality and not restful.