Poor sleep not only affects patient care -- "We know that lack of sleep degrades the quality of care for our patients and can increase medical errors," said Abdalla -- but also may also trigger symptoms of depression and anxiety. In the second study, the researchers found that health care workers who reported poor sleep also reported higher levels of stress, anxiety, and depression than health care workers who slept better. Although stress, anxiety, and depression can arise among well-rested individuals, "sleep is essential to mental health and there is a bidirectional relationship," Abdalla said.