Nitrous Oxide and EMOtional Cognition

Inclusion Criteria: * Aged 18-40 years * Good vision and hearing * Willing and able to give informed consent * Body mass index (BMI) within the range of 18-35kg/m2 (This is to ensure we exclude underweight individuals who might have more substantial reactions to the nitrous oxide). * Sufficiently fluent in English to understand tasks * Willing to avoid drinking any alcohol from 3 days prior to Visit One until the end of Visit Three * Willing to avoid using recreational drugs for 3 months prior to Visit One and throughout the duration of the study Exclusion Criteria: * Receiving or seeking treatment for any mental health condition (covered in Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders-5 (SCID) assessment in screening procedures) * History of any mental health condition (covered in SCID assessment in screening procedures) * Attention deficit hyperactivity disorder (ADHD) requiring treatment with stimulant or other centrally-acting drugs * A positive drug test for any of the following: amphetamine, barbiturates, benzodiazepines, buprenorphine, cocaine, marijuana, methadone, methamphetamine, methylenedioxymethamphetamine (MDMA), morphine, methaqualone, opiates, phencyclidine, propoxyphene, tricyclic antidepressants, tramadol, ketamine, oxycodone, cotinine, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), fentanyl, synthetic marijuana, 6-mono-acetyl-morphine (6-MAM). * Regularly drink 14 or more units of alcohol a week * Any eye, throat or ear surgery or a medical procedure requiring intravenous injection or line into a vein in the last 6 months * A head injury causing concussion or unconsciousness in the past 6 months * A collapsed lung or lung surgery (e.g., pneumothorax) * A history of cardiac arrhythmias * Current injuries of the face or mouth (including ulcers or dental problems) * Dental surgery in the past month * Deep diving or scuba diving (which has a risk of decompression sickness) in past month * Pregnancy / intention to become pregnant during the study * Breastfeeding during the study * Asthma, emphysema or any medical condition that affects the lungs or breathing * Diagnosed vitamin B12 deficiency * Any use of recreational drugs in the last three months * Participation in any other drug study in the last three months * Participation in any other study with the same tasks in the last year OPTIONAL SLEEP STUDY ADD-ON Exclusion Criteria: * Unable to undergo cardiac monitoring * Unable to wear the sleep patch device for full monitoring period * Implanted neurostimulator