The spine expands at night that mean the space between the joints may swell when this happens it can cause discomfort. This happens mostly when the spine lacks its normal curves and alignment accompanied with spinal degenerative changes. Usually, it is more affected when your bed is not properly supporting you, Depending on your sleeping position the type of mattress is really important. The proper mattress is extremely important as we sleep one third of our life. If you have any questions on mattress please let us know and put you in the right direction.