Direct Comparison of Altered States of Consciousness Induced by LSD, Psilocybin, and DMT in Healthy Participants

Inclusion Criteria: 1. Good understanding of the German language 2. Understanding of procedures and risks associated with the study 3. Willing to adhere to the protocol and signing of the consent form 4. Willing to refrain from the consumption of illicit psychoactive substances during the study 5. Willing not to operate heavy machinery within 48 h after administration of a study substance 6. Willing to use effective birth control throughout study participation 7. Body mass index 17 - 34.9 kg/m2 Exclusion Criteria: 1. Relevant chronic or acute medical condition 2. Current or previous major psychiatric disorder (e.g. psychotic disorder) 3. Psychotic disorder or bipolar disorder in first-degree relatives 4. Hypertension (SBP\>140/90 mmHg) or hypotension (SBP\<85 mmHg) 5. Bradycardia (\< 45 bpm) 6. Prolonged QTc interval (males: \>450 ms, females: \>470 ms) 7. AV block II° (Mobitz type and Webckebach type) and III° 8. Hallucinogenic substance use (not including cannabis) more than 20 times or any time within the previous two months 9. Pregnancy or current breastfeeding 10. Participation in another clinical trial (currently or within the last 30 days) 11. Use of medication that may interfere with the effects of the study medication 12. Tobacco smoking (\>10 cigarettes/day) 13. Excessive consumption of alcoholic beverages (\>15 drinks/week)