E2006-A001-108 is a 4-period crossover study designed to demonstrate that the mean change from baseline in postural stability (worsening) when participants are awakened at approximately 4 hours postdose is significantly less after lemborexant than after zolpidem tartrate extended release following a single-dose administration at bedtime.

Inclusion Criteria:

• Healthy, non-smoking female participants, aged 55 years and older, or male participants, aged 65 years and older, at the time of informed consent

• Regular sleep timing and duration, per the following criteria:

  1. Regular time in bed, between 7 and 9 hours as reported at Screening and verified by the Sleep Diary during the Screening Period before the adaptation night such that time in bed is not less than 7 hours or more than 9 hours on more than 2 of the 7 consecutive nights recorded in the Sleep Diary
  2. Regular bedtime, defined as the time the participant attempts to fall asleep, between 22:00 and 01:00 and regular waketime, defined as the time the participant gets out of bed for the day, between 05:00 and 09:00 as reported at Screening and verified by the Sleep Diary during the Screening Period before the adaptation night such that neither bedtime nor waketime is outside of the permitted time windows on more than 2 of the 7 consecutive nights

• Able to detect a 1000 Hertz (Hz) tone at 20 decibels (dB)

• Able to read English at an 8th-grade level

Exclusion Criteria:

• Is a female of childbearing potential Note: All females will be considered to be of childbearing potential unless they are postmenopausal (defined as amenorrheic for at least 12 consecutive months, and are postmenopausal without other known or suspected cause), or have been sterilized surgically (i.e., bilateral tubal ligation, total hysterectomy, or bilateral oophorectomy, all with surgery at least 1 month before dosing).
• A current diagnosis of insomnia disorder, sleep-related breathing disorder, periodic limb movements disorder (PLMD), restless legs syndrome, circadian rhythm sleep disorder, narcolepsy, sleep-related violent behavior, sleep-driving, sleep-eating, or symptoms of another parasomnia that in the investigator's opinion make the participant unsuitable for the study
• Has subjective sleep onset latency (sSOL) > 20 minutes or subjective wake after sleep onset (sWASO) > 60 minutes on more than 2 nights as reported on the Sleep Diary during the Screening Period before the adaptation night
• Latency to persistent sleep (LPS) longer than 30 minutes as measured on the PSG on the Baseline night (or repeat Baseline night, if needed)
• Has a sleep onset Rapid eye movement (REM) period, defined as first epoch of stage REM within 15 minutes of sleep onset, as measured on the PSG on either the adaptation night or Baseline night (or repeat Baseline night, if needed)
• Apnea-Hypopnea Index > 15 or Periodic Limb Movement with Arousal Index > 15 as measured on the PSG on the adaptation night
• Comorbid nocturia resulting in frequent need to get out of bed to use the bathroom during the night
• History of fracture due to a fall within the past 5 years
• Evidence of orthostatic hypotension at Screening
• Use of hearing aid or clinically significant hearing loss
• Presence or history of Meniere's disease, labyrinthitis, benign paroxysmal positional vertigo, no recent vertigo from any other cause, no recent dizziness or head injury
• Unable to stand unaided for a minimum of 2 minutes
• At Screening, fails Romberg test in the clinical judgment of the investigator
• Significant vision loss or inability to read computer screen in <80 lumens per square meter (lux) ambient illumination
• History of drug or alcohol dependency or abuse within approximately the previous 2 years or have a positive urine drug screen at Screening or Baseline
• Self-reports consuming more than 14 alcohol-containing drinks per week (females) or 21 alcohol containing drinks per week (males) at Screening
• A prolonged QT/heart rate corrected QT interval (QTc) (QT interval corrected for Fridericia's formula [QTcF] > 450 milliseconds [ms]) as demonstrated by a repeated electrocardiogram (ECG) at Screening (repeated only if initial ECG indicates a QTcF interval > 450 ms)
• Any suicidal ideation at Screening or within 6 months of Screening or any lifetime suicidal behavior
• Evidence of clinically significant disease (e.g., cardiac, respiratory, gastrointestinal, renal, psychiatric or neurological disease, malignancy other than basal cell carcinoma, or chronic pain) or condition that in the opinion of the investigator(s) could affect the participant's safety or interfere with the study assessments
• Used any prohibited prescription or over-the-counter concomitant medications within 1 week or 5 half lives, whichever is longer, before the Baseline night
• Scheduled for surgery during the study
• Transmeridian travel across more than 3 time zones in the 2 weeks before the first Baseline night, or plans to travel more than 3 time zones during the study.
• Currently enrolled in another clinical trial or used any investigational drug or device within 28 days or 5 half lives, whichever is longer preceding informed consent
• Hypersensitivity to lemborexant or zolpidem or any of their excipients
• Active viral hepatitis (B or C) as demonstrated by positive serology
• Previous exposure to lemborexant or suvorexant