Wake Up Feeling Stiff? Here's What Your Body's Trying to Tell You

After a full night's sleep, we all hope to feel rested and refreshed. But sometimes, we greet the morning with groans and grunts instead, thanks to stiff muscles.

Morning muscle stiffness is never a fun way to start the day, yet it's a common occurrence. And while its cause is usually simple — and treatable — achy muscles can occasionally indicate a more serious health issue.

Here, Alice Chen, MD, a physiatrist at the Hospital for Special Surgery (HSS), shares reasons for morning muscle stiffness, plus ways to soothe the soreness.

The root of your morning muscles stiffness could be something as simple as the way you're sleeping.

While we snooze, we can unintentionally move into some uncomfortable positions. This can result in waking up with our muscles twisted in knots.

"Sleeping with the neck and back in a contorted position (like sleeping upright in a chair or sofa) can cause joint and muscle strain," Dr. Chen says.

Indeed, any position that throws your cervical spine (the top part of your spine) out of alignment can lead to neck and backaches.

Going too hard at the gym? Your muscles may pay for it in the morning.

"After a heavy workout, muscles can feel sore because there is swelling of the muscle tissue," Dr. Chen says. And any time there's swelling, there's usually accompanying stiffness.

In addition to pushing too hard, training too much can also create problems. Your muscles require time to recover and repair between sweat sessions. When you don't give yourself adequate rest, you'll likely experience more extreme muscle soreness.

Over time, physical and emotional symptoms can result from overtraining. Look out for these signs, according to the American Council on Exercise:

• Decreased performance
• Increased perceived effort during workouts
• Excessive fatigue
• Agitation and moodiness
• Insomnia or restless sleep
• Loss of appetite
• Chronic or nagging injuries
• Metabolic imbalances
• Psychological stress and/or depression

While working out too hard (or too often) can cause stiffness, the opposite is also true. The less you move throughout the day, the more stiff you will feel come the next morning.

Long periods of inactivity, like watching TV or working a desk job, are a common cause of morning stiffness, according to Harvard Health Publishing.

And the reality is, you're most inactive when you're sleeping.

You may have noticed more morning aches and pains with the passing years. That's no coincidence.

"As the body ages, the joints experience more wear and tear," Dr. Chen says. This can cause stiffness, "especially when there are long periods of inactivity, like sleep."

Making matters worse, we tend to be more sedentary in older age. And as we know, lack of movement just makes our muscles more prone to soreness.

Believe it or not, what you put on your plate can affect whether you feel stiff when you wake up.

Here's why: Certain foods — such as those high in trans or unsaturated fats, omega-6, refined carbohydrates and added sugar — can contribute to inflammation in the body, according to the Cleveland Clinic.

These inflammatory foods can "affect the muscles (and blood vessels), making joints susceptible to swelling and pain," Dr. Chen says.

On the other hand, ‌not‌ getting enough essential nutrients, like vitamin D, can lead to issues like stiffness. Vitamin D is vital for bone and muscle health. It helps your body absorb calcium and phosphorus, which are necessary for healthy bones and tissues, according to the Cleveland Clinic.

When your body is deficient in vitamins and minerals you need, you may experience symptoms like muscle weakness, aches, cramps, bone pain and non-muscle-related symptoms like fatigue or depression.

Sometimes your morning stiffness can be a sign you're getting sick.

When your body is trying to fight off a common cold or virus, your immune system activates, triggering the release of infection-fighting white blood cells, according to UCLA Health.

"This inflammatory response is what causes the fever, aches and pains," Dr. Chen says.

The harder your body fights against the infection, the greater muscle soreness you'll experience.

Muscle stiffness is one of many ways stress manifests in the body.

When you're stressed, your body's level of the hormone cortisol increases, Dr. Chen says. In small doses, cortisol can suppress inflammation. But when you are chronically stressed, you will have consistently high cortisol, which can have the opposite effect. It creates more inflammation and a weakened immune system, according to the Cleveland Clinic.

As a result of this inflammation, you may experience more muscle pain, weakness and soreness over time, Dr. Chen says.

In addition, stress can sabotage your sleep by keeping you tossing and turning all night, making you feel achier in the a.m.

Certain medical conditions like rheumatoid or psoriatic arthritis can cause inflammation in the body, triggering soreness and pain in the joints and muscles, Dr. Chen says.

Muscle stiffness due to illness is usually called systemic muscle pain — discomfort felt throughout your entire body, according to the Mayo Clinic. This is different from muscle soreness related to overtraining or stress, which tends to be localized (only affecting a few muscles).

Other medical conditions that cause muscle pain include fibromyalgia, hypothyroidism, lupus and Lyme disease and many more, per the Mayo Clinic.

Waking up a little stiff and sore is pretty common, especially as we get older. But, morning stiffness should settle down once you start your day and begin to move around.

If your pain is lasting through the day, or is accompanied by other symptoms, talk to your doctor. They can evaluate you and help treat any underlying illness you may have.