In March 2019 researchers from the USA published the results of their study to assess whether there was any association between sleep duration and risk of common medical and mental health conditions. 771 individuals kept a sleep diary for 14 days and reported details of any medical conditions or mental health symptoms. Total sleep time, sleep quality, sleep efficiency, and circadian midpoint were then analysed. Results showed that a lower average total sleep time, and reduced sleep quality and sleep efficiency appeared to increase the risk of gastrointestinal problems, depression, and anxiety. A further analysis revealed that a greater night-night variability in total sleep time appeared to be associated with an increased risk of neurological, breathing and gastrointestinal problems, as well as pain and depression. However, night-to-night variability in sleep quality and sleep efficiency did not appear to be associated with any medical of mental health condition leaving the researchers therefore wondering whether disturbed sleep is what causes the increased risk.
Slavish DC et al. Intraindividual Variability in Sleep and Comorbid Medical and Mental Health Conditions. Sleep 2019 Mar 7. [Epub ahead of print]