A good night’s rest can be elusive, and sometimes the culprit is the wrong — or old — pillow.

Bad pillows can cause neck or shoulder pain and headaches, and they can worsen allergy symptoms, like sneezing and congestion, said Natalie D. Dautovich, assistant professor in the department of psychology at Virginia Commonwealth University and the environmental scholar for the National Sleep Foundation.

Dr. Marc Leavey, primary care specialist at Lutherville Personal Physicians, part of Mercy Medical Center in Baltimore, who speaks on sleep issues, said that because people have different sleeping patterns — side, back, stomach and restless — and there are different pillow styles and fillings, there isn’t one right pillow for everyone.

No matter how a person sleeps, Dautovich said, a great pillow allows sleepers to rest comfortably in their natural sleeping position and supports their head and neck in a neutral alignment, which means centered over their shoulders.

To sort through the different pillows out there, the sleep experts offered the following tips.

Stomach sleepers

These people need only light support, said Brandon Berman, in-house sleep expert for sleep-products company Reverie. Look for a low-loft pillow, which refers to a pillow’s height as it lies flat on the bed.

“Stomach sleepers tend to like a very thin pillow, which can be used under the head, chest or stomach,” Dautovich said.

Leavey said a thin pillow prevents stomach sleepers from hyperextending their neck. Stomach sleepers may not even need a pillow.

Back sleepers

A medium-support pillow will give back sleepers adequate support for their head and neck, the sleep experts said.

“Back sleepers may also seek out a pillow with a curved edge that allows their shoulders to remain level while elevating their head and neck,” Berman said.

Leavey and Dautovich cautioned back sleepers to ensure the pillow won’t lift their necks too high, which ends up craning the head forward. A lower-loft pillow can prevent that.

Side sleepers

Side sleepers need firm support to keep the spine aligned with the shoulders and hips, they all said. A high-loft pillow can help.

Dautovich said firmer pillows will prevent side sleepers’ heads from tipping down toward the mattress. Here’s also where the mattress comes into play, Leavey said. Ideally for side sleepers, their hips and shoulders should sink slightly into the mattress to help with that straight-spine alignment.

Restless sleepers

Leavey said restless sleepers may have a harder time fitting into these categories.

“If you’re a restless sleeper, all bets are off. You should try and look for a bolster-type pillow or a body pillow,” he suggested.

Size

Leavey said people should buy whatever size they want and not to let the size of their bed determine pillow size.

Fill

Feathers, down, synthetic, memory foam and latex are different pillow fills. Generally, down and feather blends are soft and fluffy, synthetic can still be soft but gives some resistance, and memory foam feels dense and supports the sleeper’s head, Dautovich said.

The one drawback to memory foam is that it can be hot, Leavey and Berman said. Latex is an alternative to memory foam that doesn’t get hot. Manufacturers are starting to focus on technology to make pillows cooler too. Memory foam and latex pillows might take some time to get used to, Leavey said, but they are extremely durable and can last a long time.

If possible, test pillows before buying, Dautovich and Leavey said, such as going to a bedding shop and lying down with the pillow.

“If you spend 10 minutes testing pillow options before you buy, it will be a great investment for your … sleep in the long run,” she said.

Cost

How much to spend on a pillow is a personal preference. Dautovich said sleepers should focus first on what is comfortable to them and keeps their spine straight. That said, inexpensive pillows might only last six months or a year at best, Leavey added.

Care

It’s time to replace pillows if they have lumps and sags, Dautovich said, noting that many doctors suggest replacing them every two years. Leavey recommended the fold test. If the pillow can be folded over and doesn’t spring back into shape, shop for a new one. In between purchases, wash them a few times a year, Leavey said. Dautovich added that pillows that aren’t washable can be run through the dryer on high temperatures to kill dust mites.