Musculoskeletal strain: This is the most common cause of back pain, especially after sleeping. Poor sleeping posture, an uncomfortable mattress, or a pre-existing musculoskeletal condition can lead to strain on the back muscles, resulting in pain and stiffness.

Herniated disk: A herniated disk can cause back pain, especially if it compresses a nerve root. This condition can be exacerbated by certain sleeping positions.
Degenerative disc disease: As people age, the spinal discs can degenerate, leading to back pain. Sleeping can sometimes worsen the condition due to the increased pressure on the spine.
Osteoarthritis: This is a common condition that affects the joints, including those in the spine. It can cause back pain and stiffness, especially after periods of inactivity like sleeping.

Spinal fracture: Although less common, a spinal fracture (which could be due to osteoporosis or trauma) is a critical diagnosis not to miss. It can cause severe back pain and limited mobility.
Cauda equina syndrome: This is a serious condition that occurs when the nerves in the spinal canal are compressed, leading to severe back pain, numbness, and potentially permanent nerve damage if not promptly treated.
Spinal infection (e.g., osteomyelitis, discitis): Infections of the spine can cause severe back pain and are medical emergencies. They require prompt diagnosis and treatment to prevent serious complications.

Spondylolisthesis: A condition where one of the vertebrae slips out of place, which can cause back pain and stiffness.
Ankylosing spondylitis: A type of arthritis that affects the spine, although it typically presents with chronic back pain and stiffness rather than acute episodes after sleeping.
Spinal tumor: Tumors in the spine can cause back pain, but this is a less common cause and usually accompanied by other symptoms like weight loss or neurological deficits.