Asthma is a condition in which one’s airways get narrow and swells and produces extra mucus. This can makes breathing difficult and trigger coughing, wheezing and shortness of breath. It is not clear whether there is a circadian rhythm factor responsible for these nighttime disturbances or whether sleep in some way contributes to them, but studies designed to uncover the exact influence of sleep or circadian rhythms on asthma have been largely inconclusive. Even so, many researchers believe that asthmatic symptoms are at least partly due to circadian rhythms and use the term "nocturnal asthma" to describe the phenomenon of asthma symptoms worsening at night. Not all asthma sufferers experience nocturnal asthma. Those who do should discuss their symptoms with their doctor in order to develop a treatment plan that addresses the nighttime condition. People with asthma should also be aware that nocturnal asthma is associated with more severe disease and increased mortality. Peer review refers to the work done during the screening of submitted manuscripts and funding applications. This process encourages authors to meet the accepted standards of their discipline and reduces the dissemination of irrelevant findings, unwarranted claims, unacceptable interpretations, and personal views. Publications that have not undergone peer review are likely to be regarded with suspicion by academic scholars and professionals.