Do you sleep on your back or side?  Here's the research on the 'best' sleeping positions.

 After 50 years of research, renowned sleep researcher William Dement of Stanford University reportedly said that the only solid explanation he knew of why we sleep was "because we feel sleepy".

 Although sleep may be, as one researcher put it, "the single greatest behavior in search of a function," it clearly matters to our health and well-being.

 But are we doing it right?  What does the research say about sleep positions?

 Is there a correct sleeping position?

 Most people prefer to sleep on their side.  That's good to hear, because people who sleep on their backs tend to get less sleep or trouble breathing at night.

 In most cases, we move around a lot at night.  A study of 664 sleepers found that on average, participants spent about 54 percent of their time in bed on their side, about 37 percent on their back, and about 7 percent on their front.

 Men (especially those under 35 years of age) are the most restless, have more positional shifts, and nocturnal movements of the arms, thighs, and upper back.

 This may not be a bad thing, as allowing your body to move at night is generally a good idea.

 During sleep, your body will monitor for any pain or discomfort and adjust position accordingly.  This is why we usually avoid getting bedsores (or pressure ulcers) in our daily life.

 If you feel like you can't move because your partner (or dog) is taking up too much space in the bed, consider switching sides or getting a bigger bed.

 And don't bind yourself too tightly.  Give yourself some room to move around.

 Being comfortable is the key.  There is no standard research providing clear evidence for an "optimal sleep position".  Your age, weight, environment, activities, and whether you're pregnant all play a role in which sleeping position is best for your body.

 Ideally, we can find a position that helps us get a good night's sleep, and a position that prevents us from waking up in any discomfort.

 Even with our chosen position, some configurations are better than others.  In one study, people who rested in a position where the spine rotated (such as the unsupported side position), woke up with more pain in the morning.

 However, although some forms of side sleeping can put a bit of strain on the spine, it seems that side positions are, in general, better than other options.

 Which pillow should I choose?

 Choosing the right pillow is crucial for a good night's sleep.

 Lack of support for the head and neck during sleep adversely affects spinal alignment, and causes musculoskeletal problems such as neck pain, shoulder pain, and muscle stiffness.

 Hopefully, the pillow material doesn't affect the spine.  Instead, what makes the difference is shape and height.  A UK-shaped pillow can help you get a long night's sleep, and a roll-shaped pillow can reduce morning pain and bedtime pain in chronic pain sufferers.

 Unfortunately, science has not given us an answer as to what the best mattress is.  With everyone's sleep being different, it will be difficult to compare in the long term.

 However, there are bad mattresses.  If your bed sags, loses its firmness, becomes a noisy spring, or shows obvious signs of wear and tear, consider replacing your mattress.

 Rotating a mattress can help prolong its life and improve comfort.  This should be done at least once or twice a year.

 Other Tips for a Restful Night's Sleep

 Set the cold room temperature.  The ideal temperature for sleep is 18.3°C (between 15-19°C);  High temperatures can affect sleep.

 Allow some air flow in the room.  In addition to bringing in nice, fresh air, it also clears any accumulated heat, keeping us nice and cool at night.

 Some medications, such as certain types of antihistamines, can make it easier to fall asleep.  On the other hand, stimulants like caffeine can greatly affect the quality of your sleep.

 Finally, make sure not to go to bed with a full bladder, as getting up to urinate at night can affect sleep.