Should Lexapro Be Stopped Before MSLT?
Yes, escitalopram (Lexapro) must be discontinued at least 2 weeks before the Multiple Sleep Latency Test (MSLT) to ensure valid results. 1
Why SSRIs Like Lexapro Must Be Stopped
Antidepressants that suppress REM sleep—including all SSRIs like escitalopram—directly alter MSLT outcomes and can mask narcolepsy. 1 The evidence is compelling:
Patients who discontinued REM-suppressing antidepressants (REMS-ADs) before MSLT were 12 times more likely to demonstrate ≥2 sleep-onset REM periods (SOREMPs) compared to those who remained on these medications (odds ratio: 12.20; 95% CI: 1.60-92.94). 1
Patients who tapered off REMS-ADs had significantly shorter mean sleep latencies (8.77 vs 10.21 minutes, P = 0.009) and more than double the odds of meeting diagnostic criteria for narcolepsy (≥2 SOREMPs) compared to those not taking antidepressants at all (odds ratio: 2.22; 95% CI: 1.23-3.98). 1
The American Geriatrics Society explicitly recommends that sedating medications—which include antidepressants with sedating properties—should be discontinued before MSLT. 2
Specific Taper Timeline for Lexapro
Discontinue escitalopram 2 weeks prior to MSLT. 1 This is the standard protocol used at major sleep centers:
- Most antidepressants require a 2-week washout period 1
- Fluoxetine is the exception, requiring 6 weeks due to its long half-life 1
- Escitalopram has a half-life of approximately 27-32 hours, making 2 weeks adequate for complete clearance
Additional Critical Pre-MSLT Requirements
Beyond stopping Lexapro, several other steps are mandatory:
Discontinue Other Interfering Medications
All stimulants (amphetamines, methylphenidate, modafinil) and sedating agents (benzodiazepines, hypnotics, antihistamines) must also be stopped before MSLT. 2, 3
Document Adequate Sleep for 7-14 Days
Use wrist actigraphy for 7-14 days before MSLT to objectively verify adequate sleep duration and resolve chronic sleep debt. 2, 4, 3 This is critical because:
- Chronic sleep deprivation is the most common cause of false-positive MSLT results 3, 5
- Sleep logs overestimate sleep time by approximately 1.5 hours per night; only actigraphy shows a significant relationship between nighttime sleep duration and MSLT outcomes 4, 3
- Adults require ≥6 hours total sleep time on the overnight polysomnography immediately before MSLT 4
Verify Compliance with Urine Drug Screen
Perform urinary drug screening following overnight polysomnography, as 16% of patients test positive for undisclosed substances that invalidate MSLT interpretation. 6 Patients frequently do not self-report medication use. 6
Common Pitfall: Inadequate Washout Period
If escitalopram is not discontinued or the washout period is insufficient, the MSLT interpretation must include a statement that REM-suppressing medication may have affected the results and potentially masked narcolepsy. 1
- In one study, 30% of patients remained on REMS-ADs during MSLT, leading to potentially missed diagnoses 1
- Five patients in a case series had false-positive results from accumulated sleep debt alone, which would have led to inappropriate psychostimulant prescriptions 5
Clinical Context
The MSLT should only proceed after:
- Lexapro tapered off for ≥2 weeks 1
- Actigraphy confirms 7-14 days of adequate sleep (≥6 hours/night for adults) 2, 4, 3
- Overnight polysomnography documents ≥6 hours total sleep time 4
- All other REM-suppressing and alertness-altering medications discontinued 2, 3
- Urine drug screen performed 6
Failure to meet these conditions will compromise diagnostic accuracy and may result in misdiagnosis of narcolepsy or idiopathic hypersomnia. 1, 6