Short-term administration of nitrous oxide (N2O) increases power in the theta frequency range (4-7 Hz) of the electroencephalogram (EEG) after the gas is withdrawn, but does not affect delta frequency (0.5-4 Hz) power. In a study of 14 healthy male participants, those receiving 50% N2O either continuously for 20 minutes or in two 10-minute inhalations showed rapid EEG transitions during gas administration and withdrawal. Power in high-frequency gamma bands increased during N2O, while beta and alpha frequencies decreased. After withdrawal, theta power increased in several electrodes, with negligible differences between the two treatment groups. The effect was reproducible with repeated dosing.
Nitrous oxide, increasingly used for sedation and pain control rather than general anesthesia, produces highly variable subjective experiences that are not always pleasant. In twenty healthy male volunteers who inhaled 50% nitrous oxide for 20 minutes, qualitative analysis of open-ended responses revealed two overarching themes: the drug is mind-altering and causes sensory overload. Mind-altering effects included dreamlike states—encompassing changes in consciousness and scary, bizarre, or transcendental dreams, but no pleasant dreams—and heightened emotions such as euphoria, anxiety, and fear of losing control. Sensory overload comprised distorted perception, bodily sensations, and a heightened sense of surroundings. These findings help clinicians understand patient likes and dislikes during nitrous oxide sedation.