A solvent can be defined as “a liquid that has the ability to dissolve, suspend or extract other materials, without chemical change to the material or solvent”. Numerous chemical or technical processes rely on these specific properties of organic solvents in industry. Occupational exposure to solvents is not rare and some activities may cause substantial exposure to these substances in the workforce. Short-term or acute exposures cause a prenarcotic syndrome, and long lasting exposure conditions have been associated with various neurological and neuropsychiatric disorders, e.g., anosmia, hearing loss, colour vision dysfunctions, peripheral polyneuropathy and depression, but most significantly with the gradual development of an irreversible toxic encephalopathy. For the last 3 decades reports and epidemiological studies have been published reporting sleep disturbances among other complaints, related to long-term exposure to these compounds. In addition, the question has been posed if solvents can be the cause of a sleep apnoea syndrome in exposed workers, or on the contrary, if these workers are misdiagnosed and ‘common’ sleep apnoea syndromes are the cause of their chronic symptoms of fatigue and memory and attentional disturbances.