Can falling asleep on coach cause back injury

[bunnings]

Hi last few weeks l deveoped back pain in the lower back, its only a slight pain nd most of the time l dont notice it , its worst when l wake up in bed in the morning, but its been there a few weeks and wont go away, A few times l have falled asleep on a single couch sitting upright watching TV at night , l was wondering if you think thats what caused it, l cannot think of any other cause. Also when should l see a doctor if it doesnt go away. IF its only a slight pain does that mean its most likely not serious.