Study to Evaluate SAGE-324 in Participants With Essential Tremor

Inclusion Criteria: 1. Diagnosis of ET, as defined by all of the following criteria: * Isolated tremor syndrome consisting of bilateral upper limb action tremor * At least 3 years duration * With or without tremor in other locations (eg, head, voice, or lower limbs) 2. Absence of other neurological signs, such as dystonia, ataxia, or parkinsonism, isolated focal tremors (eg, voice, head), task- and position-specific tremors, sudden tremor onset, or evidence of stepwise deterioration of tremor. 3. Participant has the following: * Scores of at least 12 in the combined TETRAS Performance Subscale Item 4 (upper limb tremor) at both Screening and pre-dose on Day 1 * Scores of at least 6 in the total TETRAS Performance Subscale Item 4 score for the dominant upper limb (the sum of the three items for either the right or left upper limb, whichever is dominant) at both Screening and pre-dose on Day 1 4. Participant has a baseline TETRAS ADL Subscale score of at least 20 at Screening. 5. Willing to discontinue medications taken for the treatment of ET except propranolol at least 14 days or 5 half-lives (whichever is longer) prior to receiving the investigational product (IP). Medications taken for the treatment of ET that were discontinued prior to receiving IP may be resumed following Day 97. Participants in the adjunct therapy cohort must be on a stable dose of propranolol (maximum total daily propranolol dose up to 320 mg allowed) for the treatment of ET from 3 months prior to Screening through Day 97 of the study. 6. Participant is willing to limit use of alcohol to 2 units per day for males and 1 unit per day for females starting at least 1 week prior to Day 1 and through Day 97 of the study. 7. Participant is willing to maintain prestudy consumption of products that contain nicotine starting at least 1 week prior to Day 1 and through Day 97 of the study. Exclusion Criteria: 1. Presence of known causes of enhanced physiological tremor. 2. Participant has had newly administered tremorgenic drugs (14 days or 5 half-lives \[whichever is longer\] prior to Day 1) or presence of alcohol withdrawal state. 3. Direct or indirect injury or trauma to the nervous system within 3 months before the onset of tremor. 4. Previous procedure for the treatment of ET, deep brain stimulation, brain lesioning, or magnetic resonance (MR) guided procedure, eg, MR-guided focused ultrasound. Use of Cala Trio bracelet for the treatment of ET from two weeks prior to Day 1 through Day 97 is prohibited. 5. Participant has had botulinum toxin for treatment of ET within 6 months of Screening. 6. Historical or clinical evidence of tremor with functional neurological syndrome origin. 7. Participant currently requires propranolol treatment for a medical condition other than ET. 8. Participant has history of substance abuse or dependence prior to Screening, has a positive screen for drugs of abuse at Screening or predose on Day 1. Participants with nicotine use disorder that impacts their tremor are excluded.