The Claim

Consumption of 240 mg of caffeine from coffee or energy drinks three hours before bedtime in young healthy adults is associated with a significant decline in subjective sleep quality, with the proportion reporting poor sleep increasing from 21.6% at baseline to 29.7% after coffee and 46.6% after energy drinks, indicating a dissociation between objective sleep metrics and perceived sleep quality.

Source: Effects of Caffeine Intake on Self-Administered Sleeping Quality and Wearable Monitoring of Sleep in a Cohort of Young Healthy Adults

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
46score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Correlation
1 study reviewed
In plain English

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.

See the scientific wording

Young healthy adults who consume 240 mg of caffeine from coffee or energy drinks three hours before bedtime report a significant decline in subjective sleep quality, with the proportion reporting poor sleep increasing from 21.6% at baseline to 29.7% after coffee and 46.6% after energy drinks, indicating a dissociation between objective sleep metrics and perceived sleep quality.

Why this might work

Caffeine sticks to brain receptors that normally calm the brain down when tired, preventing those receptors from doing their job. This keeps the brain more active than it should be during sleep, making the person feel like they didn’t sleep well even though their body slept the same as usual.

Verified mechanismbased on 1 study

What the research says

1 study

  1. Study: Effects of Caffeine Intake on Self-Administered Sleeping Quality and Wearable Monitoring of Sleep in a Cohort of Young Healthy Adults

    Even though their sleep looked the same on their smartwatches, many young adults felt they slept worse after drinking coffee or energy drinks before bed — especially energy drinks, where almost half felt their sleep was poor. The study confirms this feeling isn’t just in their heads; it’s real, even if their sleep didn’t actually change.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

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