A good night’s sleep should leave you feeling rested and refreshed. But if you regularly wake up with a headache, your pillow could be contributing to the problem.

The wrong pillow can affect the alignment of the neck and spine, aggravate allergies or prevent muscles from relaxing properly during sleep. Knowing what to look for can help determine whether it’s time for a change.

1) Your pillow is the wrong height.

A pillow that is too high or too low can interfere with the natural alignment of the cervical spine. Poor alignment can create muscle tension, pressure on the neck and, in some cases, nerve irritation that contributes to morning headaches.

Sleep position makes a difference. Side sleepers generally need enough pillow height to fill the space between the shoulder and head, while back sleepers typically need less elevation. Stomach sleepers usually require a thinner pillow.

An adjustable pillow can make it easier to find a comfortable height.

2) Your pillow may be aggravating allergies.

Pillows can collect dust mites and other allergens over time. Some people may also be sensitive to materials used inside pillows, including feathers or certain synthetic fibers.

Allergic reactions can cause nasal congestion and sinus pressure, which may contribute to headaches.

Regularly washing pillowcases and following the manufacturer’s cleaning instructions can help, but older pillows may eventually need to be replaced. Hypoallergenic pillows and protective covers can also help reduce exposure to allergens.

3) It doesn’t support your sleeping position.

A pillow that works well for one sleeping position may be uncomfortable in another.

A thicker pillow may provide appropriate support for a side sleeper but place excessive strain on the neck of someone who sleeps on their stomach.    People who frequently change positions during the night may benefit from an adjustable pillow that accommodates several sleeping positions.

The goal is to keep the head, neck and spine as naturally aligned as possible.

4) Your pillow is sagging.

Pillows lose their shape and support over time.

A flattened, sagging or lumpy pillow can create uneven pressure around the head and neck and force muscles to work harder while you sleep. That tension can contribute to neck pain and morning headaches.

If a pillow no longer returns to its normal shape or has developed permanent lumps or flat areas, it may be time to replace it.

5) It may aggravate a sleep disorder.

For people with certain sleep disorders, pillow choice can be particularly important.

A pillow that positions the head or neck poorly may worsen snoring or interfere with comfortable breathing. People with sleep apnea or other diagnosed sleep conditions should discuss sleep positioning and pillow selection with a health care professional rather than relying solely on a new pillow to address symptoms.

Those who grind their teeth may also experience jaw and facial tension that contributes to headaches.

6) Your pillow traps too much heat.

Sleeping too hot can interfere with sleep quality, while dehydration can also contribute to headaches.

Some pillow materials retain more heat and moisture than others. People who frequently wake up sweating or feeling overheated may benefit from pillows made with more breathable materials.

A cooler sleeping environment and adequate hydration throughout the day can also help improve sleep comfort.

7) It isn’t relieving tension in your neck.

Stress can cause people to carry tension in their shoulders and neck, even while sleeping.

A supportive pillow should allow the neck muscles to relax rather than forcing them to compensate for an awkward sleeping position. When the pillow provides too little or too much support, muscle tension may continue throughout the night and contribute to a tension headache the following morning.

Is it time to replace your pillow?

There is no single replacement schedule that works for every pillow because materials and construction vary. Instead, pay attention to its condition.

A pillow that has become permanently flattened, lumpy or uncomfortable is no longer providing the same support it once did.

Persistent odors can also indicate that a pillow needs to be cleaned or replaced. Waking with congestion, watery or itchy eyes, coughing or other allergy symptoms may indicate allergens in the bedding or sleeping environment.

Choosing the right pillow

Choosing the right pillow depends largely on sleeping position, body size, mattress firmness and individual health needs.

Look for a pillow that keeps the neck and head in a neutral position and maintains its shape throughout the night. Adjustable pillows allow sleepers to change the height or firmness, while breathable materials may be preferable for people who tend to sleep hot.

People with chronic neck or back pain, recurring headaches, sleep apnea or other health conditions should consider discussing pillow selection and sleep positioning with a health care professional.

Morning headaches can have many causes, and changing a pillow won’t solve every case. Persistent or worsening headaches, particularly those accompanied by other symptoms, should be evaluated by a medical professional.

But for some people, the solution may begin with something simple: replacing an old, uncomfortable pillow with one that provides better support.