Nitrous oxide is unique in that it is none-invasive and has a rapid onset of action, making it a valuable option in a variety of emergent situation and in painful paediatric procedures. The present randomised controlled study was set up in order to explore the effects of 3 different concentrations of nitrous oxide, 40, 55 and 70 vol. % as compared to placebo, provided by self administered from a demand valve by healthy volunteers for a short 4-minute period evaluating effect on attention, mode and wakefulness. Onset time and peak reduction in attention, change in saccadic eye movements, showed a dose dependent pattern. After brief use, saccadic eye movements returned to baseline within minutes after cessation of administration. Loss of consciousness was observed only during administration of the 70 vol. %, minor side effects such as dizziness and nausea was observed during inhalation of all three active treatments. The risks for over sedation/unconsciousness has to be weighed against the clinical benefit of faster and more pronounced effects if a 70 % fixed nitrous oxide concentration is to be used by self administration from a demand valve.