(CNN) You're exhausted, your body yawning for sleep. Yet once your head hits the pillow, your mind is flooded with worry, making sleep elusive, at times impossible.
Don't fret, experts say: There are relaxation techniques you can use to calm that racing mind.
"Think of these relaxation exercises as tools in your tool kit for better sleep," said sleep specialist Rebecca Robbins, an instructor in the division of sleep medicine for Harvard Medical School.
"Practice them, and you'll get better and better at falling asleep, which is the holy grail, right? No one wants to spend time tossing and turning at night."
Deep breathing is a science-backed method of calming the body and mind that can be done easily before you get into bed and when you wake during the middle of the night.
Changing the rhythm of your breath slows your heart rate, reduces blood pressure and stimulates the body's parasympathetic "rest and digest" system, which can take worry and anxiety offline.
"Consciously focusing on the breath can help you separate yourself from the darting thoughts that fly through your brain," Robbins said.
There are a number of deep breathing techniques you can try. Diaphragmatic breathing, also known as belly breathing, focuses on relaxing the diaphragm, the main muscle of respiration. Start by taking a deep breath through your nose to a slow count of six, making sure that you can feel your stomach rise with your hand as it fills with air. Count to six again as you let the breath slowly escape.
"Strive for effortless inhales that are soft and soundless while treating your exhales like gentle, extended sighs of relief," suggested CNN contributor Dana Santas, a certified strength and conditioning specialist and mind-body coach.
Stay in the moment, Santas said, by focusing on the sounds and sensations of your breath: "Direct all of your senses to follow the path of air in through your nose, down your throat, into your lungs and out again. If your mind wanders, bring it back to your breath, happening in the here and now."
Meditation is a centuries-old method of calming the body and the mind. Studies show it can help perfectionists stop judging themselves and can assist in the treatment of smoking, pain, addictive disorders and depression, among others.
Using direct measures of brain function and structure, one study found it only took 30 minutes a day of meditation practice over the course of two weeks to produce a measurable change in the brain.
"When these kinds of mental exercises are taught to people, it actually changes the function and the structure of their brain," neuroscientist Richard Davidson, professor of psychiatry at the University of Wisconsin-Madison and the founder and director of the Center for Healthy Minds, told CNN in an earlier interview.
There are many resources on the internet to help someone begin to meditate. Davidson and his colleagues have created a free, science-based app designed to help people practice meditation and mindfulness.
Visualization is another sleep aid. Picture a calm and peaceful spot in your mind's eye and fill it with specific objects, colors and sounds. Researchers have found that people who visualize in detail were able to push unwelcome thoughts more successfully from their minds.
If you have trouble populating the scene, the researchers suggest asking yourself questions about smell, touch and light, such as "Can I feel the sun on my skin? What do I smell in the air?"
You can also visualize your body relaxing, experts say. While breathing deeply and slowly, imagine your breath is a wind coursing through the body, easing stress and relaxing tension as it moves through each part of the body and then escapes.
"I like to think of the breath as a light in your mind's eye that grows when you inhale and gets smaller as you exhale," Robbins said. "Those tangible strategies where you visualize something and match that to a breath are really powerful."
Most of us aren't even aware of how much tension we carry in our muscles until it shows up in backaches and headaches.
Progressive muscle relaxation is a way of relaxing those muscles, thus making it easier to fall asleep, experts say. You tense and release muscle groups in the body in a certain order, starting at the head and working your way down to the toes and feet.
Each section of the body is tightly tensed and held for 10 seconds as you breathe in. Strive to squeeze each muscle hard, but not to the point of cramping or pain. Then, as you breathe out, relax the muscle suddenly and all at once. University of Michigan Health recommends you do the exercises in a systematic order that you can find here.
There's an added benefit to the exercise, experts say: There's no room in your brain for anxious thoughts.
Here's a way to stop your mind from repetitively listing all the things you need to do (or haven't done), but it only works if you do it before you hit the sack.
"Don't worry in bed. Schedule a 'worry time' -- a period of time outside of the bedroom, outside of sleep, to worry about the things that naturally creep in your mind at night," said sleep specialist Dr. Raj Dasgupta, an assistant professor of clinical medicine at the Keck School of Medicine at the University of Southern California.
"Write down a list of things you need to do tomorrow," suggested Dr. Vsevolod Polotsky, a professor of medicine and director of sleep research at the Johns Hopkins University School of Medicine.
"You can even email it to yourself. It gives you satisfaction and the realization that it is night and there's nothing you can do with your list, but you can attend to it tomorrow," Polotsky said.
All these mental tricks and relaxation tips serve a purpose beyond that night's sleep, experts say.
"They are extremely beneficial from a classical conditioning standpoint," Robbins said. "If your body knows what comes after the end of these activities is sleep, then you start to condition yourself, and after a bit of time, your body will more easily slip into a state of relaxation, which increases your chances of sleep."