A very brief self-report scale for measuring insomnia severity using two items from the Insomnia Severity Index - development and validation in a clinical population

Trials used in this analysis: ClinicalTrials. gov identifier: NCT01105052 (https: //www. clinicaltrials. gov/ct2/show/NCT01105052) (sample b), ClinicalTrials. gov identifier: NCT01256099 (https: //clinicaltrials. gov/ct2/show/NCT01256099) (sample c and d), German clinical trial (DRKS), registration ID: DRKS00008745 (https: //www. drks. de/drksweb/navigate. do? navigationId=trial. HTML&TRIALID=DRKS00008745) (sample e), ClinicalTrials. gov identifier: NCT01663844 (https: //clinicaltrials. gov/ct2/show/NCT01663844) (sample f and g), ClinicalTrials. gov Identifier: NCT02743338 (https: //clinicaltrials. gov/ct2/show/NCT02743338) (sample h).