Zopiclone, a widely used hypnotic drug, is frequently found in blood samples taken from drivers suspected of driving under the influence. In this study, the investigators aim to correlate zopiclone serum concentrations with degrees of driving impairment in healthy volunteers by use of a validated driving simulator. The investigators also aim to compare their results with the results from a previous study that investigated zopiclone impairment of cognitive and psychometric tests.

Inclusion Criteria:

• Male
• Caucasian ethnicity
• Age 25-35 years
• Possession of a driver's licence for at least five years

Exclusion Criteria:

• Score ≥ 2 on the modified Apfel-scale to assess risk for motion sickness(*)
• History of driving under the influence of alcohol and/or illicit substances
• History or presence of alcohol or illicit drug abuse
• Former abnormal reaction to any hypnotic drug
• History of strong averse reactions to blood sampling procedures
• Regular (daily) intake of any prescribed drug, or intake of grapefruit juice or herbal remedies that can influence the metabolism of zopiclone (e.g. St John's wort)
• History of severe allergic reactions, or significant mental, cardiovascular, renal or hepatic disorder, or other significant disease as judged by the investigators
• Detection of any drugs of abuse on pre-session urine drug screening

(*)Modified Apfel-criteria for prediction of postoperative nausea/vomiting:

1. Smoker? yes 0, no 1
2. History of nausea and/or vomiting following surgery, dental treatment, injections or similar procedures? yes 0, no 1
3. History of car sickness after 10 years of age? yes 0, no 1

A score of two or more points excludes participation.