The Study
Effects of Caffeine Intake on Self-Administered Sleeping Quality and Wearable Monitoring of Sleep in a Cohort of Young Healthy Adults
This study watched what happened when people drank coffee or energy drinks before bed and asked them how they slept. It found that even though their watches didn't show they slept less, they felt like they slept worse. But we can't say the caffeine caused that feeling — maybe they were stressed or ate junk food, and that's what really made them feel tired.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Scientists gave young adults coffee or energy drinks with caffeine right before bed and checked if they slept worse—using watches and their own feelings.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 546 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Even if your body sleeps the same, you might feel like you slept poorly after caffeine—especially from energy drinks—without feeling tired the next day.
- 2Watches showed no change in sleep time or deep sleep.
- 3But 30% felt they slept worse after coffee, and 47% felt worse after energy drinks—even though their sleep didn't actually change on the watch.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Nutrients
Year
2025
Authors
J. Schlichtiger, Stefan Brunner, Anna Strüven, J. M. Hoppe, C. Stremmel
Related Content
Claims (6)
Consuming 240 mg of caffeine three hours before bedtime does not change total sleep time, deep sleep, light sleep, time awake, or heart rate during sleep in young healthy adults.
Young healthy adults who drink coffee or energy drinks containing 240 mg of caffeine three hours before bed report worse sleep quality than before, with energy drinks causing a larger drop in perceived sleep quality than coffee, even when objective sleep measures do not change similarly.
People who drink energy drinks with 240 mg of caffeine report poor sleep more often than people who drink coffee with the same amount of caffeine.
Young healthy adults who drink caffeine report more trouble falling asleep and more nighttime awakenings, but they do not feel sleepier during the day or need sleep medication as a result.
Wearable sleep trackers accurately measure sleep duration, quality, and stages in healthy people without changing how they sleep, making them suitable for studying sleep patterns across large populations in everyday life.
Consuming caffeine within six hours of bedtime reduces the total amount of sleep and decreases slow-wave sleep.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.