Objectives: To gain insight into how social distancing impacts human life and how it may induce stress, anxiety, depressive-symptoms, sleep disturbance, and mental challenges during the pandemic; and to evaluate the effects of a complementary therapy named Smarto-One on improving these health impacts. Methods: Participants, men and women aged 20-65, were randomly assigned to the interventional Smarto-One group (n=259) or placebo group (n=68). Participants orally self-administered Smarto-One or placebo for 20 consecutive days. Online surveys were completed by the participants the day before the 20-day treatment start date and the day following treatment end date. Fifteen participates from Smarto-One group and fifteen participates from placebo group participated in electroencephalography (EEG) during sleep before and after the 20-day intervention. The primary outcome measures were sleep duration and self-evaluated stress. Results: We found 1) during social distancing due to the COVID-19 pandemic, stress/depression led to sleep disturbance and mental issues; 2) participants taking Smarto-One showed significant improvements in stress/depression levels, sleep duration and wake-up mood/symptoms compared to placebo; and 3) participants taking Smarto-One showed significantly improved deep sleep time (slow-wave sleep, SWS, N3) of non-rapid eye movement (non-REM) sleep as measured by EEG. Conclusions: This study illustrates the value of Smarto-One as an effective remedy that improves mental health and well-being under conditions including social distancing and stress/depression.