Is the bedroom your favorite spot in the house – a restful retreat where you feel an instant sense of calm and peacefulness, where you have little trouble falling and staying asleep, and where you awaken refreshed and ready to greet the new day? If not, the room’s layout, décor, and furnishings may literally be keeping you up at night.

Designing your bedroom with rest in mind is especially important considering that half of Americans sometimes have trouble sleeping, according to the National Sleep Foundation. And we’re paying the price in terms of poor health, lowered productivity, moodiness, trouble concentrating, and even weight gain.

Luckily, turning your bedroom into a sleep-friendly zone isn’t difficult and doesn’t have to be expensive – but it does require some careful thought about how to set the stage for sleep. "The bedroom should be your cocoon," says Joyce Walsleben, Ph.D., an associate professor at New York University’s Sleep Disorders Center and coauthor of A Woman’s Guide to Sleep: Guaranteed Solutions for a Good Night’s Rest (Three Rivers Press). "You want to create a room that’s quiet, dark, comfortable, and safe."

Try these tips to do just that – sweet dreams are sure to follow.

Choose calming colors

Stick with soft, restful hues or rich, sedate tones. Soothing blues and greens are among the most popular bedroom colors, and for good reason: They’re associated with feelings of peace, calm, and serenity. Sedate neutrals and gentle earth tones are other good choices. Deep, rich colors like chocolate, eggplant, and even red aren’t off limits in the bedroom – just make sure they’re on the warm and cozy end of the spectrum. Stay away from stimulating, bright shades and avoid high-contrast color schemes – they’re too jarring in a space meant for rest and relaxation.

Invest in a good mattress

If your mattress is more than seven years old, it’s probably letting you down when it comes to proper support. (Hint: If you wake up tired and achy or if you sleep better in hotels than at home, your bed has seen better days.) Plus, after seven years – during which you’ve likely logged more than 20,000 hours there – "your mattress has doubled in weight from dead skin cells, sweat, oil, fungus, dust mites, and their feces," says Michael Breus, Ph.D., a professor at the Atlanta School of Sleep Medicine and author of Good Night: The Sleep Doctor’s 4-Week Program to Better Sleep and Better Health (Dutton). When shopping for a new model, "what’s most important is comfort and support – and that’s a very individual thing," says Breus, who suggests logging at least 15 minutes in the showroom on each bed you’re considering. For durability, look for a mattress with a coil count above 375 and a coil thickness of 13 or less (the lower the number, the thicker the coil). If your mate tosses and turns, opt for pocketed coils to help insulate you from all the rocking and rolling. Size counts, too: If you have room in your space and in your budget, buy the biggest bed you can – especially if you share your bed or have pint-sized nocturnal visitors. Don’t be duped into spending too much, though – a recent Consumer Reports comparison found that all but the cheapest mattresses can be a good choice, whether they cost $700 or more than $4,000. Whatever you choose, rotate the mattress every few months to ensure that it wears evenly.

Do some pillow talk

Replace synthetic pillows at least every three years, and natural pillows at least every seven years – after which point they not only play host to the critters listed above, but have likely lost their loft and springiness. As with mattresses, what makes a "good" pillow is subjective – but in general, go for a medium pillow if you sleep mostly on your back, a firm pillow if you’re a side-sleeper, and a soft pillow if you log a lot of time on your tummy. "The right pillow supports and positions your head correctly and keeps your spine in alignment while you sleep," Breus explains. And if you have allergies, consider hypoallergenic down, cotton, wool, or synthetic fills. (Note: The higher the thread count on the pillow cover, the less likely that filling is to migrate out.) Or try an Asian-style buckwheat pillow (available from www.PillowCompany.com and www.SitInComfort.com), whose hulls mold themselves around your head and neck and provide proper support while you sleep.

Make slipping between the sheets a treat

Nix polyester, fleece, and satin sheets – all of which can trap heat and moisture – in favor of 100-percent cotton, which breathes well and feels deliciously soft and smooth next to your skin. Fine Egyptian or pima cotton sheets are considered the best; cotton with a sateen finish is silky, while percale is wonderfully crisp. The higher thread count your sheets sport, the more sumptuous they’ll feel and the longer they’ll last. Aim for a minimum of 200 threads per inch (check the package for this info), and up to 400 if you really want something luxurious. But don’t waste your money on threat counts higher than 400 – they’re more marketing hot air than smart sleep investment.