Part 1 is a single ascending dose (SAD) trial in healthy volunteers (HV) to assess the safety, tolerability, and pharmacokinetic (PK) profile of orally administered LYT-300.

Part 2 is a crossover assessment in HV of the effects of food on the safety, tolerability, and PK profile of orally administered LYT-300.

Part 3 is a multiple ascending dose (MAD) trial in HV to assess the safety, tolerability, and PK profile of multiple doses (up to 7 days) of orally administered LYT-300.

Part 4 is an assessment of the effects of LYT-300 vs. placebo on pharmacodynamic and patient reported outcome response to a validated clinical model of anxiety.

Part 1: This is a randomized, double-blind, placebo-controlled, SAD design to assess the safety, tolerability, and PK profile of orally administered LYT-300 in HV, in a 3-period, 3-sequence, crossover, dose escalation design.

Part 2: This is a randomized, open label, 3-period, 3-sequence, crossover assessment of the effects of food on the PK, safety, and tolerability of orally administered LYT-300 in HV. A single dose of LYT-300 will be administered on 3 occasions, separated by a minimum 7-day washout period. Part 2 is planned as a single dosing cohort.

Part 3: This is a randomized, double-blind, placebo-controlled, sequential, MAD trial in HV to assess the safety, tolerability, and PK profile of multiple doses (up to 7 days) of orally administered LYT-300. This part will include ascending doses given either once daily in the morning (QAM), once daily in the evening (QHS), or twice daily (BID).

Part 4: This is a double-blind, randomized assessment of the effects in HV of a single dose of LYT-300 vs. placebo on pharmacodynamic and patient reported outcome response to a validated clinical model of anxiety.

Main Inclusion Criteria:

Parts 1, 2, 3 and 4: Healthy Volunteers

1. Male or female between 18 and 55 years old (inclusive) at the time of screening.
2. In good general health at screening, free from clinically significant unstable medical, surgical or psychiatric illness, at the discretion of the Investigator.

Main Exclusion Criteria:

Parts 1, 2, 3 and 4: Healthy Volunteers

1. Evidence or history of any condition or situation that adversely impacts a normal sleep-wake cycle.
2. Confirmed COVID-19 infection within 2 months of screening, known exposure to another person with COVID-19 within 14 days of screening
3. History of illness with fever within 28 days prior to the first dose.
4. A history of, or current evidence for, serious mental illness

Parts 1, 2 and 3 are double blind during the data collection. Determination for dose escalation may be made under unblinded conditions by assessors.

Part 4 consists of 2 groups. Group 1 (the validation group) will be single-arm placebo. Group 2 (the test group) will be double blind during data collection.