I have been taking Prozac (fluoxetine) 20 mg and Vyvanse (lisdexamfetamine) 30 mg for two months; they were effective but now I am having difficulty falling asleep. What should I do?

Adjust Vyvanse Timing and Consider Cognitive Behavioral Therapy for Insomnia

The most likely cause of your sleep difficulty is Vyvanse (lisdexamfetamine), as insomnia is a well-documented adverse effect of this stimulant medication, and you should first try taking it earlier in the morning and implementing sleep hygiene measures before adding any sleep medication. 1

Understanding the Problem

Your situation involves two medications with opposing effects on sleep:

• Vyvanse (stimulant): The FDA label explicitly lists insomnia as a common adverse reaction (≥5% incidence) 1. Stimulants increase dopamine and norepinephrine, which promote wakefulness and can significantly interfere with sleep initiation 2

• Prozac (fluoxetine): While less likely the primary culprit after 2 months, fluoxetine can cause or worsen insomnia in some patients through increased arousal, eye movements during non-REM sleep, and transient arousals 3. However, most fluoxetine-related sleep disturbances that occur early in treatment typically resolve over time 4

Immediate Action Steps

1. Optimize Vyvanse Timing

• Take Vyvanse immediately upon waking (as early as possible in the morning)
• The medication has a long duration of action, so even morning dosing can affect evening sleep
• Never take it in the afternoon or evening

2. Implement Sleep Hygiene and Behavioral Interventions

Cognitive Behavioral Therapy for Insomnia (CBT-I) should be your first-line treatment for the insomnia itself 5. The American College of Physicians strongly recommends CBT-I as initial treatment for chronic insomnia disorder with moderate-quality evidence 5. This includes:

• Stimulus control: Use bed only for sleep; leave bedroom if unable to fall asleep within 20 minutes
• Sleep restriction: Limit time in bed to actual sleep time, then gradually increase
• Sleep hygiene: Consistent sleep schedule, avoid screens before bed, cool dark room
• Relaxation techniques: Progressive muscle relaxation, breathing exercises

3. Reassess Medication Effectiveness

You mention the medications "worked 2 months now is not" - this suggests possible tolerance or inadequate dosing of your ADHD treatment. Discuss with your prescriber:

• Whether Vyvanse dose needs adjustment (maximum 70mg/day for ADHD) 1
• Whether the initial therapeutic effect has diminished
• Alternative ADHD medications with less sleep impact

When to Consider Adding Sleep Medication

Only if CBT-I and timing adjustments fail should you consider adding pharmacologic therapy for sleep, using shared decision-making with your physician 5. The evidence for sleep medications is generally low-quality, and they carry risks including:

• Cognitive impairment and next-morning drowsiness 6
• Falls and fractures (especially concerning with stimulants that may affect balance)
• Potential for dependence
• Association with dementia, major injuries, and possibly cancer with long-term use 6

Critical Pitfalls to Avoid

⚠️ Do not take Vyvanse later in the day - this will worsen insomnia

⚠️ Do not abruptly stop either medication - withdrawal from stimulants can cause depression, fatigue, and hypersomnia 1

⚠️ Avoid combining multiple sedating medications without medical supervision - the interaction risks are significant

⚠️ Do not use alcohol or over-the-counter sleep aids without discussing with your doctor - these can interact dangerously with your current medications

Serotonin Syndrome Warning

Be aware that combining Prozac (an SSRI) with certain other medications increases risk of serotonin syndrome, which can include agitation and insomnia among more serious symptoms 1. If you develop agitation, confusion, rapid heart rate, or muscle rigidity, seek immediate medical attention.

Next Steps with Your Prescriber

Schedule an appointment to discuss:

1. Whether Vyvanse is still effectively treating your ADHD symptoms
2. Optimizing timing of Vyvanse administration
3. Referral for CBT-I (can be delivered via app, phone, or in-person) 5
4. Whether a brief trial of dose reduction or medication holiday on weekends might help assess the sleep impact
5. Only if above measures fail: short-term pharmacologic sleep aid with careful monitoring

The goal is to maintain effective ADHD treatment while restoring normal sleep, prioritizing non-pharmacologic interventions first given their superior safety profile and lack of tolerance development.