A number of conditions may develop, or worsen, during prolonged stays bed. Bedsores can be a nightmare. Maintaining one position in bed encourages the development of pneumonia and impairs re-expansion of a lung damaged by a respiratory disease.
The contraction of some muscles and stretching of others can cause crippling knee stiffness and also a type of paralysis called foot drop. These can take weeks to correct. There is general weakening of the muscles and joints. When bones are not used, the calcium drains from them inviting osteoporosis and fractures.
The drain of calcium can lead to kidney and bladder stones. A horizontal position can make it difficult for men particularly to urinate. Such urinary retention can then cause bed wetting.
After a few days in bed indigestion often develops, along with loss of appetite. Constipation is almost inevitable with the absence of muscular movement and the difficulties in using a bedpan. The retained mass of feces may then overflow as diarrhea.
Sleeplessness at night results from too much inactivity and napping during the day. Staying in bed can cause emotional stress marked by irritability and hypochondria, often leading to lethargy and depression.