About the sleeping pills, there are a few factors. Under sedation or after a stroke you move around less and secretions can pool in the lowest part of the lungs allowing bacteria to thrive. Sedation will also sedate the cilia, the little hairs of the cells lining the lungs, which act as an escalator to move bacteria and gunk (technical term) up and out. Also after a stroke or if someone is over-sedated the muscles which protect the airway can become unco-ordinated and allow food and saliva into the lungs carrying bacteria.