☕ That Morning Caffeine May Be Hurting Your Sleep

From the Desk of a Doctor Newsletter

☕⚠️ The Caffeine Double-Edged Sword: New Research Shows Prolonged Sleep Disruption

Caffeine helps us feel alert, focused, and productive. But at higher doses, its effects may last far longer than we realize — even after the buzz fades.

A 2025 randomized, double-blind, placebo-controlled crossover trial (PMID: 39377163) found that a single 400 mg dose of caffeine, even when taken early in the morning, significantly disrupted sleep up to 12 hours later (that’s basically 1 grande Starbucks coffee folks…)

The study:
👥 12 healthy adults (habitual caffeine users, ~190 mg/day)
🧪 Four controlled sleep conditions with washout periods
🛌 Sleep assessed using overnight polysomnography (gold standard)

In contrast, 100 mg of caffeine — whether taken in the morning or afternoon — had no measurable impact on sleep architecture or perceived sleep quality.

Why this matters:
Caffeine’s half-life varies widely between individuals. While the stimulating effects may feel gone by evening, physiological effects can persist, subtly degrading sleep depth and continuity — even in habitual users.

Takeaway:
Caffeine is a dose-dependent trade-off. Moderate intake may be sleep-neutral, but higher doses can quietly erode sleep quality, even when consumed early in the day.

If you’ve been reading my emails in the last few months, you’ve learned that coffee is absolutely “good for you” — but you should be cutting it off early in the day and moderating the total amount of caffeine you ingest.

— Dr. Myro Figura

🔗 Read the study here

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