Dayvigo (Lemborexant) in Adults 65 and Older: Geriatric Impact and Clinical Guidance

Why Age Matters for Lemborexant Dosing

Physiologic aging changes how the body handles lemborexant in ways that directly affect both efficacy and safety. Older adults typically carry more body fat, have reduced hepatic cytochrome P450 3A4 (CYP3A4) activity, and produce less plasma albumin, all of which alter drug distribution and clearance.

Pharmacokinetic Changes After Age 65

The FDA-approved prescribing information for lemborexant reports that maximum plasma concentration (Cmax) is approximately 45% higher and area under the curve (AUC) is roughly 52% greater in subjects aged 65 and older compared with younger adults [1]. This exposure difference is not trivial. Higher AUC means residual drug levels persist into the next morning, which is the mechanistic basis for the next-day psychomotor warnings specific to this age group.

The apparent terminal half-life extends to roughly 55 hours in older adults, compared with 17 to 19 hours in younger subjects [1]. That prolonged half-life raises the possibility of drug accumulation with nightly dosing, particularly in patients who also take moderate CYP3A4 inhibitors such as fluconazole or diltiazem. Clinicians should review the full interaction profile before initiating therapy.

Why the 5 mg Starting Dose Was Selected

The FDA required a dedicated geriatric pharmacokinetic analysis as part of the lemborexant new drug application. Based on population pharmacokinetic modeling, the agency concluded that the 5 mg dose provides therapeutic exposure in adults 65 and older while keeping peak concentrations below the threshold associated with significant next-morning impairment in the majority of patients [1]. The 10 mg dose remains available but carries an explicit labeling caution for this population, particularly regarding driving ability the morning after use.

Phase 3 Evidence in Older Adults: SUNRISE-1 and SUNRISE-2

Two key trials, SUNRISE-1 and SUNRISE-2, provide the clinical evidence base for lemborexant across the adult age spectrum, with pre-specified subgroup analyses in subjects aged 65 and older.

SUNRISE-1: Head-to-Head Against Zolpidem Extended-Release

SUNRISE-1 (N=1,006) was a 1-month randomized controlled trial that compared lemborexant 5 mg, lemborexant 10 mg, and zolpidem extended-release 6.25 mg against placebo in adults with insomnia disorder [2]. The trial included a significant proportion of patients aged 55 and older. Lemborexant 5 mg produced statistically significant improvements in sleep onset latency and sleep efficiency versus placebo (P<0.001 for both endpoints), and demonstrated non-inferior sleep onset and statistically superior sleep maintenance compared with zolpidem ER at the end of the treatment period [2].

The 65-and-older subgroup mirrored the overall direction of these findings, though absolute magnitudes were modestly higher, consistent with the pharmacokinetic differences described above.

SUNRISE-2: Long-Term Efficacy at 12 Months

SUNRISE-2 (N=949) extended follow-up to 12 months, making it one of the longest placebo-controlled trials ever conducted for a prescription sleep agent in a general adult insomnia population [3]. Patients were randomized to lemborexant 5 mg, lemborexant 10 mg, or placebo. Both doses maintained statistically significant reductions in subjective sleep onset latency (sSOL) and wake after sleep onset (WASO) versus placebo through month 12 (P<0.001) [3].

At month 6 in the full trial population, lemborexant 5 mg reduced sSOL by approximately 18 minutes versus placebo. Discontinuation due to adverse events occurred in 3.4% of the 5 mg group versus 2.4% for placebo over 12 months, a difference that did not reach statistical significance [3]. The proportion of patients aged 65 and older enrolled in SUNRISE-2 was approximately 20%, providing a meaningful geriatric subset for safety analysis.

What the SUNRISE Data Do Not Show

Neither SUNRISE trial was powered for a primary endpoint exclusively in adults 65 and older. Subgroup estimates carry wider confidence intervals. Clinicians should treat the age-stratified data as hypothesis-generating and apply clinical judgment for individual patients, particularly those with multiple comorbidities or polypharmacy burdens common in this age group.

Fall Risk and Next-Morning Psychomotor Impairment

Fall-related injuries are the leading cause of injury death in adults aged 65 and older in the United States, with approximately 36 million falls reported annually according to CDC surveillance data [4]. Any sleep medication that impairs balance, reaction time, or postural stability carries real potential for harm in this population.

Driving Simulation Studies

The FDA required a dedicated next-morning driving study for lemborexant. A randomized, double-blind, placebo- and active-controlled crossover trial measured standard deviation of lateral position (SDLP) in a driving simulator 9 hours after drug administration in adults aged 65 and older [5]. At the 10 mg dose, SDLP was significantly increased versus placebo the morning after a single nighttime dose in older subjects. At 5 mg, the increase was smaller and did not reach statistical significance in the primary analysis, though individual variability was notable [5].

The FDA responded to this data by adding a specific warning in the Dayvigo prescribing information: patients taking lemborexant 10 mg should not drive or operate heavy machinery the morning after use [1]. Patients taking 5 mg should exercise caution until they know how the drug affects them individually.

Beers Criteria and Orexin Antagonists

The American Geriatrics Society (AGS) Beers Criteria 2023 updated its recommendations regarding sleep agents [6]. All sedative-hypnotics, including orexin receptor antagonists such as lemborexant and suvorexant, are listed with a cautionary recommendation in adults 65 and older, noting evidence for increased risk of adverse cognitive and motor events. The 2023 update acknowledges that orexin antagonists have a different, more targeted mechanism than benzodiazepines or Z-drugs, but the Criteria panel concluded that sufficient evidence to remove them from the caution list was not yet available [6].

Prescribers should document a benefit-risk discussion with every older patient before initiating lemborexant.

A Practical Risk-Stratification Approach for Clinicians

Geriatric patients starting lemborexant can be stratified by fall risk at baseline:

• Low fall risk (no prior falls in 12 months, normal gait on Timed Up and Go test <12 seconds): 5 mg is reasonable with standard counseling on next-morning effects.
• Moderate fall risk (one prior fall, mild gait slowing, or use of one CNS-active medication): 5 mg with a trial home safety assessment; consider scheduling a follow-up at 2 weeks.
• High fall risk (two or more falls in 12 months, use of multiple CNS-active agents, or abnormal Timed Up and Go >20 seconds): non-pharmacologic interventions should be exhausted first; if lemborexant is used, start at 5 mg with close monitoring and inform the patient and caregivers about fall precautions.

This framework does not replace individualized clinical assessment but provides a structured starting point for documentation.

Cognitive Effects in Older Adults

Cognitive safety is as pressing as fall safety in geriatric populations. Benzodiazepines and Z-drugs are associated with acute delirium and, in longer-term use, with increased dementia risk according to pharmacoepidemiologic studies. The question for clinicians is whether lemborexant shares these risks.

Mechanism: Why Orexin Blockade Differs

Lemborexant works by blocking orexin-1 and orexin-2 receptors, which are the primary wake-promoting neuropeptide system [7]. Unlike benzodiazepines, lemborexant does not broadly potentiate GABA-A receptor activity across the entire brain. This selectivity is the theoretical basis for the expectation of less next-day cognitive fog, less amnesia, and lower delirium risk.

A 2019 paper published in the Journal of Clinical Sleep Medicine compared cognitive function assessments between lemborexant and zolpidem ER in the SUNRISE-1 population and found no statistically significant difference in cognitive composite scores between lemborexant 5 mg and placebo after 1 month [8]. Zolpidem ER showed a trend toward greater impairment on the Digital Symbol Substitution Test at the 1-month assessment, though the comparison was not pre-specified as a primary endpoint [8].

Long-Term Cognitive Data: What Is Still Missing

No randomized controlled trial has followed older adults taking lemborexant for longer than 12 months with validated cognitive endpoints (such as the Montreal Cognitive Assessment or formal neuropsychological battery) as primary outcomes. The 12-month SUNRISE-2 trial collected adverse event data on cognitive symptoms but was not designed as a cognitive safety trial [3].

This gap is clinically meaningful. Providers caring for patients with mild cognitive impairment (MCI) or early dementia should weigh the absence of long-term cognitive safety data carefully. A 2023 systematic review in Sleep Medicine Reviews examined orexin receptor antagonists in patients with neurodegenerative disorders and concluded that current evidence is insufficient to establish safety or efficacy in this subpopulation [9].

Comorbidities and Drug Interactions Common in the 65+ Population

Cardiovascular Comorbidities

Lemborexant is primarily metabolized by CYP3A4. Older adults with atrial fibrillation or heart failure frequently receive diltiazem or verapamil, both moderate CYP3A4 inhibitors. Co-administration with diltiazem is expected to increase lemborexant AUC by approximately 2-fold based on drug interaction modeling in the FDA label [1]. The prescribing information recommends limiting lemborexant to the 5 mg dose when co-administered with moderate CYP3A4 inhibitors, and contraindicates co-administration with strong CYP3A4 inhibitors such as clarithromycin or itraconazole [1].

Depression and Anxiolytic Use

Older adults with comorbid depression frequently receive SSRIs, SNRIs, or low-dose tricyclic antidepressants for sleep. None of these agents cause clinically meaningful CYP3A4 inhibition, so pharmacokinetic interactions are not a primary concern. CNS additive effects, however, remain a consideration. The SUNRISE trials excluded patients taking prescribed sedatives, opioids, or anxiolytics at baseline, meaning the real-world older adult population on multiple psychotropic agents is less well-characterized in the trial data.

Opioid Co-Administration

The FDA labeling includes a specific warning against concurrent use with opioids due to risk of excessive CNS depression, respiratory depression, and death [1]. Given that a substantial proportion of older adults with chronic pain receive opioid analgesics, this contraindication has practical significance. If insomnia treatment is needed in a patient on chronic opioids, non-pharmacologic interventions such as cognitive behavioral therapy for insomnia (CBT-I) should be the first-line approach per American Academy of Sleep Medicine guidelines [10].

Comparing Lemborexant to Other Options for Geriatric Insomnia

Versus Benzodiazepines and Z-Drugs

Benzodiazepines such as temazepam are explicitly listed by the AGS Beers Criteria 2023 as drugs to avoid in older adults due to risks of falls, fractures, motor vehicle accidents, and cognitive impairment [6]. Z-drugs (zolpidem, eszopiclone, zaleplon) are also flagged with a "strong" recommendation to avoid in this population. Lemborexant does not carry a "avoid" designation in the 2023 Beers Criteria; it carries the more moderate "use with caution" language [6].

From a pharmacologic standpoint, this distinction reflects the mechanistic difference. It does not mean lemborexant is risk-free in older adults.

Versus Suvorexant (Belsomra)

Suvorexant (Belsomra) was the first FDA-approved dual orexin receptor antagonist and was studied specifically in a geriatric trial. A 4-week, double-blind, placebo-controlled study of suvorexant in adults aged 65 and older (N=243) demonstrated significant improvement in sleep maintenance versus placebo [11]. Suvorexant is approved at 10 mg in older adults (versus 20 mg in younger adults), reflecting a similar age-based dose adjustment philosophy to lemborexant. No head-to-head randomized trial between lemborexant and suvorexant in adults 65 and older has been published as of this writing.

Versus Low-Dose Doxepin

Low-dose doxepin (Silenor) 3 mg and 6 mg is FDA-approved for insomnia characterized by difficulty with sleep maintenance [12]. Mechanistically, it works by antihistaminic blockade at H1 receptors. A trial in adults 65 and older (N=240) showed 3 mg doxepin significantly improved WASO and total sleep time at 3 months [12]. Doxepin at these doses lacks the anticholinergic burden of higher tricyclic doses, but clinicians should still assess individual anticholinergic sensitivity in frail older adults.

Practical Prescribing Guidance for Clinicians

Starting, Titrating, and Stopping

Start lemborexant at 5 mg in all patients aged 65 and older. Administer no more than 30 minutes before bedtime, only when the patient can devote at least 7 hours to sleep [1]. If 5 mg is tolerated but insufficiently effective after 2 to 4 weeks, the prescribing information allows titration to 10 mg, but this requires an explicit benefit-risk discussion regarding next-morning impairment [1].

Discontinuation does not require a taper based on available data. No rebound insomnia signal emerged in the SUNRISE-2 discontinuation analysis at 12 months [3]. Clinicians should monitor patients for 1 to 2 weeks after stopping, since insomnia can recur independently of drug withdrawal.

Counseling Points for Patients and Caregivers

Patients aged 65 and older starting lemborexant should receive counseling on these specific points:

• Take the tablet no more than 30 minutes before intending to sleep, with at least 7 hours available before needing to be alert.
• Do not drive or operate machinery if you feel groggy the next morning, regardless of how many hours have passed since the dose.
• Tell your pharmacist and every prescriber about lemborexant, because CYP3A4 interactions can increase drug levels significantly.
• If you experience unusual behaviors during sleep (sleepwalking, sleep-driving), stop the medication and contact your provider immediately; such behaviors have been reported with lemborexant and with other hypnotics and prompted an FDA class warning for orexin antagonists [1].

When to Consider Non-Pharmacologic Treatment Instead

Cognitive behavioral therapy for insomnia (CBT-I) is recommended by the American Academy of Sleep Medicine as the first-line treatment for chronic insomnia disorder in adults of all ages, including older adults [10]. CBT-I produces durable improvements in sleep onset latency, sleep efficiency, and wake after sleep onset without medication-related risks. A 2021 meta-analysis of CBT-I in adults aged 60 and older (pooled N=1,460 across 14 randomized trials) found a standardized mean difference of 0.82 for sleep efficiency at post-treatment, with effects maintained at 6-month follow-up [13].

Lemborexant is appropriate when CBT-I is unavailable, has been tried and failed, or when the severity of insomnia warrants concurrent pharmacotherapy while behavioral treatment is being initiated.

Regulatory History and FDA Labeling Updates Relevant to Older Adults

The FDA approved lemborexant in December 2019 for insomnia disorder in adults [1]. In 2022, the FDA issued a class-wide safety communication for orexin receptor antagonists, including both lemborexant and suvorexant, regarding complex sleep behaviors such as sleepwalking and sleep-driving [1]. These behaviors, although rare, have resulted in serious injuries and deaths. The updated labeling includes a contraindication for patients with a history of complex sleep behaviors with any hypnotic, and the FDA required a Medication Guide to be dispensed with each prescription.

The labeling also specifies that drug exposure is higher in women than in men across all age groups, an effect that compounds the age-related pharmacokinetic differences. Older women, therefore, represent the highest-exposure subgroup and may benefit from the most conservative starting approach.