If people are out of sync, they can wake up feeling groggy, and find it difficult to focus the next day. But even when you think you've done everything right — you went to bed on time and got a good eight hours of sleep — you may still wake up tired and irritable.
According to sleep experts, this could be because of the way you're sleeping.
Shelby Harris, a sleep medicine expert and a professor at Albert Einstein College of Medicine told Popular Science that if your sleeping position isn't working for you, there are things you can do to change it.
Most people sleep on their sides, according to the National Sleep Foundation, but this position can cause shoulder and hip pain. Also, sleeping on your right side may even aggravate heartburn, some research found.
The theory is that a muscle in your esophagus that keeps acid in your stomach and out of your throat is loosened by the position, so some acid creeps up and causes a burning sensation. If you sleep on your left side, this muscle keeps the gap shut.
Harris said you should try sleeping on your left side if you get heartburn. Also, you should buy pillows that are thick enough to support your head, and tuck a pillow under your knees to support your lower back.
The absolute worst sleeping position, Harris said, is lying on your stomach. Only 7% of people do this, but it puts pressure on your entire body. You're likely to wake up with numbness and tingling, and it can increase the chance of muscle and joint pain. To make it easier on your body, Harris said you can use a flatter pillow to reduce neck strain.
The best position is sleeping on your back, which only 8% of people do. It's the best position for reducing aches and pain, and it doesn't cause heartburn because your head is elevated above your chest.
Of course, lying on your back increases the risk of snoring. If you're prone to sleep apnea, it might not be the position for you, although there are exercises you can try to reduce snoring.
If you'd like to change your style, Harris said you can put pillows on both sides of your body, and one under your knees. This should stop you moving around too much. If this doesn't work, you can sew a tennis ball into the lining of your shirt, so the discomfort makes you flip back over if you try and turn.
"Although it is commonly recommended that sleeping on your back is the best position to sleep in, comfort is key," Harris said. "If you're in pain or uncomfortable from your sleep position, it can definitely impact your sleep quality."
So if you find you're often waking up groggy, and you're not sure why, try changing your sleeping position. You might find you get up well rested for once.