How to Improve Posture While Sleeping
To improve your posture while you're sleeping, place a pillow under your knees if you sleep on your back, which will help align your back in the optimal position. Or, if you sleep on your side, place a pillow between your knees to keep your hips aligned and prevent you from twisting in your sleep. If you're a stomach sleeper, try to start sleeping on your back or side since sleeping on your stomach puts pressure on your spine and can cause pain and numbness.
Assess your current sleep posture. The most important thing to do in order to improve your sleep posture, is to choose positions that helps keep your spine in alignment. If you have chronic problems with headaches, back pain, heartburn, sleep apnea, and/or fatigue, your sleep positions may be exacerbating these problems. Therefore, it is good to sleep either on your back or on your side. If you tend to sleep on your side, place a pillow between your knees in order to keep your hips aligned, and to prevent you from twisting to rest your knee on the mattress. If you tend to sleep on your back, you can also place a pillow underneath your knees to make sure your back is in the optimal position. However, be aware that if you snore or have sleep apnea, this position will only exacerbate these issues. If you are a stomach sleeper, then you likely need to work the most to improve your sleep posture, as this is typically considered the worst sleeping posture. Sleeping on your stomach forces you to turn your head to the left or to the right, creating pressure on the spine. If you use a pillow, it also pushes your head higher than the rest of your spine. This can lead to pain, numbness, and tingling. If you are a stomach sleeper or find yourself waking up on your stomach, you can place a thin pillow underneath your pelvis and stomach to try and take some of the pressure off of your neck. Change your sleeping position. At first, it will probably be challenging to sleep in a position that is not the one you are used to. However, over time, you will become more comfortable. If you aren't comfortable, you may wake up in the middle of the night or feel like you aren't getting enough sleep. Falling asleep in a comfortable position is extremely important when it comes to waking up feeling refreshed. Use lots of pillows. If you want to start sleeping on your back, place extra pillows underneath each arm, one under your knees, and possibly even one on each side of your torso. If you want to sleep on your side, place a pillow between your knees, and one or two pillows behind your back to prevent you from rolling onto your back. By using pillows, you help your body stay in the new sleeping posture. Be patient. Since it is difficult to control your body position after you've fallen asleep, trying to change your sleep posture can be challenging. However, over time your new posture will improve your sleep quality and will eventually feel even more comfortable than your old posture. Improve your posture during the day. In order to improve your posture during the night, you should also work to improve your posture during the day, as this also contributes to aches and pains that may force us into a particular posture. You may not immediately know what proper posture should feel like, so you should check your posture against a wall several times a day as you begin a back and shoulder strengthening routine. Stand against the wall. For most people with poor posture, their shoulder blades do not touch the wall. Pull your shoulder blades down and in so that they connect with the wall. Next, lengthen your neck as if someone is pulling the back of your head up. Move it back until your head touches the wall. Move your chin until it is parallel to the ground. Make sure you stand with equal weight in both legs. Move to a mirror and mimic the pose to ensure your neck and shoulders are straight. Pull your shoulders down as far as possible. Tighten your abdominal muscles. Consider seeking the help of a physical therapist. If you have trouble maintaining proper posture, you may need to seek the assistance of a physical therapist, who can show you stretching exercises that will help strengthen your core. Assess your current mattress. Mattresses generally should be replaced about every 10 years, and more often if you can afford it. However, if your mattress is becoming saggy or lumpy, if you wake up with aches and pains, or if you find that you sleep better when you are away from home than in your own bed, it may be time to start searching for a new mattress. Learn about how to choose the right mattress. There are many things to consider when purchasing a mattress that is best suited for you. Therefore, you should take some time to learn about how to choose a mattress. It is a good idea to choose a firmer mattress, as a firm mattress provides better support for your skeleton. If you cannot afford to replace your mattress, you can try flipping over your current mattress and placing a piece of plywood underneath in order to provide a bit more support. Assess your current pillow. There are many factors that affect how often you should replace your pillow, including the quality and type of filling in your pillow. However, like your mattress, if you wake up with a sore neck or a headache, it's probably a good time to look for a new one. To help you determine whether or not your pillow is worn out, you can perform the “fold test”. Fold your pillow in half for thirty seconds and then release it. If it doesn't spring back into its original form relatively quickly, it's likely time for a new one. Finally, if you notice that your pillow is very lumpy or that there is a large dent where your head usually goes, it's likely time for a new one. Learn about how to choose the right pillow. As with choosing a mattress, there are many things to consider when choosing a pillow. Take the time to learn how to choose the correct pillow for you. Since you will likely be learning to sleep either on your side or on your back, you will do best with a medium thick to thick pillow, that provides good support for the neck. Make sure that any pillow you purchase keeps your neck in a straight line with your spine. You do not want the pillow to make your neck go higher or lower than the rest of your spine. Check the temperature of your room. Make sure the temperature in your room is cool, but not cold. Most people sleep best around 72° F or 22° C Eliminate noise. This may not be completely in your control, but do your best to keep your sleeping room as quiet as possible. Invest in ear plugs, or use something such as a fan to mask any outside noise. Avoid heavy, fatty meals before bed. Especially if you wish to sleep on your back, you should avoid eating a large meal before bed. Give yourself at least two hours to digest your meal. If you consume a large, fatty meal, you are more likely to feel uncomfortable while sleeping. Try to avoiding eating a heavy meal after about 6pm. Walk around for a few minutes before going to bed. If you have just risen from a seated position, then it is likely your pelvis is tucked forward and you have poor posture. Do the wall test and walk around your house to loosen your muscles. Go to bed at the same time each night, wake up at the same time each morning. In order to get the best sleep possible, it is important that you create a sleep routine that you can stick to every day of the week, including weekends. By going to bed and getting up at the same time each day, you help your body know when to be ready for sleep. If you end up going to bed later than normal one night, you should still do your best to get up at the same time. This way you don't disrupt your routine as much. If you feel very tired, try taking a short, mid-day nap to help you rather than sleeping in later or going to bed earlier. Just be sure to keep the nap to under 45 minutes. Have a bed time ritual. Each night, before going to sleep, have a ritual that you do in the same order to signal to your body that it is time to sleep. For example, you might brush your teeth, wash your face, and change in to your pajamas. You might then do some very gentle stretching or yoga. Finally, you can really get into rest mode by reading for a few minutes before turning out the lights. It is best not to let electronics, such as smart phones, televisions, or lap tops be a part of your bed time routine. While entertaining, the backlights from these devices can be stimulating and can even suppress melatonin production. Move around when you wake up. Walk around, swing your shoulders in their sockets and do very light stretches. This can ease pain and stiffness, improving posture during the day. 
Assess your current sleep posture. Change your sleeping position. Use lots of pillows. Be patient. Improve your posture during the day. Assess your current mattress. Learn about how to choose the right mattress. Assess your current pillow. Learn about how to choose the right pillow. Check the temperature of your room. Eliminate noise. Avoid heavy, fatty meals before bed. Walk around for a few minutes before going to bed. Go to bed at the same time each night, wake up at the same time each morning. Have a bed time ritual. Move around when you wake up. 