Fermented blueberry leaf tea significantly improved sleep efficiency and wake after sleep onset compared to placebo over two weeks in adults with poor sleep, with greater benefits observed in individuals with worse baseline sleep.
Key Findings
Results
The active group showed significant improvements in sleep efficiency and wake after sleep onset (WASO) compared to the placebo group after two weeks of fermented blueberry leaf tea consumption.
Per-protocol analysis included 22 participants in the active group and 20 in the placebo group
Improvements in sleep efficiency and WASO were statistically significant (p < 0.05)
Participants consumed fermented blueberry leaf tea three times daily for two weeks
Sleep was objectively measured using actigraphy
Results
No significant differences were observed between active and placebo groups for sleep latency, total sleep time, or subjective sleep quality assessments.
Sleep latency and total sleep time were assessed objectively via actigraphy
Subjective sleep quality was evaluated using the Oguri-Shirakawa-Azumi Sleep Inventory MA (OSA-MA) version questionnaire
The absence of subjective improvement despite objective gains suggests the effect may be below participants' perceptual threshold or limited to specific sleep continuity parameters
Results
Baseline sleep efficiency and WASO were negatively correlated with their respective improvements, indicating that individuals with poorer initial sleep benefited most from the intervention.
Participants with lower baseline sleep efficiency showed greater improvement in sleep efficiency
Participants with higher baseline WASO showed greater improvement in WASO
This correlation pattern suggests the intervention may be particularly relevant for individuals with fragmented sleep
The study population was adults aged 20–69 years who self-reported poor sleep
Methods
The trial was a two-week randomized, double-blind, placebo-controlled design enrolling 50 adults with poor sleep.
Participants were aged 20–69 years and reported poor sleep quality at enrollment
Randomization allocated 25 participants to the active group and 25 to the placebo group
The active intervention was fermented blueberry leaf tea, rich in hyperoside, consumed three times daily
The trial was registered with the University Hospital Medical Information Network (UMIN000055879) on 21 October 2024
Background
Blueberry leaves are rich in hyperoside and are suggested to influence sleep through serotonergic and melatonergic pathways.
Hyperoside is identified as a key bioactive compound in blueberry leaves
The proposed mechanism involves influence on serotonergic and melatonergic pathways
Prior to this trial, sleep-enhancing effects of fermented blueberry leaf tea had not yet been demonstrated
The potential of blueberry leaf products to help maintain sleep quality had been previously noted but not confirmed in controlled trials
Background
The study was motivated by the need for safer, food-based alternatives to pharmacological sleep interventions, which carry risks of dependency and adverse effects.
Pharmacological sleep interventions are noted to be associated with risks of dependency and adverse effects
The authors frame fermented blueberry leaf tea as a potential functional food approach to sleep health
The findings are described as supporting 'the potential role of functional foods in sleep health strategies'
What This Means
This research suggests that drinking fermented blueberry leaf tea three times a day for two weeks can improve certain aspects of sleep quality in adults who report sleeping poorly. Specifically, people who drank the blueberry leaf tea woke up less during the night and had better overall sleep efficiency compared to those who drank a placebo tea. These improvements were measured objectively using wrist-worn actigraphy devices, making the findings more reliable than self-report alone. Interestingly, the tea did not appear to help people fall asleep faster or sleep longer in total, and participants themselves did not report feeling that their sleep had improved on questionnaires.
One notable finding was that people who started the study with worse sleep—more nighttime awakenings and lower sleep efficiency—tended to benefit the most from the tea. This suggests the product may be especially relevant for individuals whose main sleep problem is fragmented or interrupted sleep rather than difficulty falling asleep. The blueberry leaves used in the tea are rich in a compound called hyperoside, which researchers believe may work through brain pathways involved in serotonin and melatonin, two chemicals closely linked to sleep regulation.
This research matters because many people struggle with poor sleep but are reluctant to use prescription or over-the-counter sleep medications due to concerns about side effects and dependency. A naturally derived tea that improves sleep continuity within just two weeks could offer a practical, low-risk option to explore. However, the study was relatively small (50 participants total) and short in duration, so larger and longer trials would be needed to confirm these findings and better understand who benefits most.