Recent animal studies have supported that Lactobacillus plantarum PS128 (PS128) can reduce the severity of anxiety and depression. However, previous studies did not focus on the sleep quality and mood of humans. This study determines whether PS128 reduces the severity of anxiety and depressive symptoms, regulates autonomic nervous system function, and improves sleep quality. Forty participants between 20 and 40 years of age with self-reported insomnia were randomly assigned to two groups, a PS128 group and a placebo group, in a double-blind trial. Participants took two capsules of either PS128 or a placebo after dinner for 30 days. Study measures included subjective depressive symptoms, anxiety and sleep questionnaires, and miniature-polysomnography recordings at baseline and on the 15th and 30th days of taking capsules. Overall, all outcomes were comparable between the two groups at baseline and within the 30-day period, yet some differences were still found. Compared to the control group, the PS128 group showed significant decreases in Beck Depression Inventory-II scores, fatigue levels, brainwave activity, and awakenings during the deep sleep stage. Their improved depressive symptoms were related to changes in brain waves and sleep maintenance. These findings suggest that daily administration of PS128 may lead to a decrease in depressive symptoms, fatigue level, cortical excitation, and an improvement in sleep quality during the deep sleep stage. Daily consumption of PS128 as a dietary supplement may improve the depressive symptoms and sleep quality of insomniacs, although further investigation is warranted.

Background: Diabetic retinopathy (DR) is the most common microvascular complication of type 2 diabetes mellitus (T2DM), yet DR screening coverage remains inadequate worldwide. Diabetic autonomic neuropathy typically precedes DR, and heart rate variability (HRV) provides a non-invasive autonomic measure; however, whether HRV can screen for DR remains unexplored. Methods: This pilot study investigated whether sleep-onset minute-scale HRV indices—SDANN1 (standard deviation of 1-min segment means of normal-to-normal intervals) and SDANN2 (2-min segments)—serve as candidate screening biomarkers. Using a public 24-h Holter ECG dataset of T2DM inpatients (N = 39; 11 DR-positive, 28 DR-negative), sleep-onset time-points from cardiopulmonary coupling analysis were used to extract 30 min of post-onset ECG. Results: SDANN1 was significantly lower in the DR group (median 23.6 vs. 44.8 ms, p = 0.028, d = 0.74), with an area under the receiver operating characteristic curve of 0.731 (95% CI: 0.530–0.901). At the optimal threshold of ≤ 25 ms, the odds ratio was 8.1 (95% CI: 1.7–38.4), with DR prevalence of 58% in the high-risk versus 12.5% in the low-risk group. Among 12 candidates, only the SDANN family reached significance. Conclusions: sleep-onset minute-scale HRV shows promise as a candidate risk-stratification biomarker for DR; prospective longitudinal validation in larger, sex-balanced cohorts is required before any screening application.