Publication analysis on insomnia: How much has been done in the past two decades?

Insomnia has been a rising public concern in recent years. As one example of a multidisciplinary topic, the theme of insomnia research has gradually shifted over time; however, there is very little quantitative characterization of the research trends in insomnia. The current study aims to quantitatively analyze trends in insomnia publications for the past 20 years. We retrospectively analyzed insomnia-related publications retrieved from PubMed and Google Scholar between 1994 and from a number of different perspectives. We investigated the major areas of research focus for insomnia, journal characteristics, as well as trends in clinical management and treatment modalities. The resulting 5841 publications presented an exponential growth trend over the past two decades, with mean annual growth rates at nearly 10% for each publication type. Analysis of major research focuses indicated that depression, hypnotics and sedatives, questionnaires, and polysomnography are the most common topics at present. Furthermore, we found that while studies on drug therapy and adverse effects decreased in the most recent five years, the greatest expansion of insomnia publications were in the areas of cognitive behavioral therapy for insomnia (CBT-I) and alternative therapies. Collectively, insomnia publications present a continuous trend of increase. While sedative and hypnotic drugs dominated the treatment of insomnia, non-pharmacological therapies may have great potential for advancement in future years. Future research effort is warranted for novel tools and clinical trials, especially on insomnia treatments with inadequate evidence or not-yet-clear efficacy and side effects.