Field studies and laboratory experiments on noise-induced sleep disturbance show conflicting results and do not provide sufficient knowledge for valid exposure-effect relationships. It is also well known that habituation exists for awakenings whereas other effects such as heart rate reactions and minor EEG-reactions do not habituate. In this paper comparisons are made between findings from a series of laboratory and field studies on effects of road traffic noise on sleep performed by this athor. Possible reasons for the discrepancies found in various studies in laboratory and field are commented on and methods and research needs are discussed. Comparison of results obtained in research on perceived sleep quality parameters at this Department that used the same methods in laboratory and field studies showed fairly good agreement for difficulties in falling asleep and perceived sleep quality whereas awakening reactions were much less frequently reported in the field studies.