Efficacy of Polygonatum Sibiricum on Sleep Quality Improvement

Inclusion Criteria: * Male and female volunteers who are between the ages of 20 and 65 * Experienced any of the following sleep problems, at least more than once a week for more than 2 months: 1) difficulty in falling asleep or staying asleep; 2) waking up at dusk and not being able to fall asleep again; 3) not feeling refreshed even after getting some sleep. Exclusion Criteria: * Diagnosed with insomnia assessed with a structured interview and sleep scale measurements * Possibility of drug-induced sleep disorders due to current intake of medication (i.e., corticosteroid, statin, etc) * Had taken sleeping pills (i.e., zolpidem, benzodiazepine) during the past 2 months * Diagnosed with any major medical or neurological disorders assessed during medical history taking, physical examination or experimental tests. * Diagnosed with any axis 1 psychiatric disorders (depressive disorder, bipolar disorder, alcohol dependence, schizophrenia) evaluated with a structured instrument * A history of traumatic brain injury with loss of consciousness, or any contraindications to MRI (i.e., claustrophobia, metallic foreign devices in body) * Had taken psychotropic drugs within the past 3 months before study participation * Allergic to polygonatum sibiricum or experienced side effects after consumption of any product containing polygonatum sibiricum * Participated in another clinical trial or took other medications during the period that may influence the results of this clinical trial * Currently taking contraceptive pills * Planning for pregnancy during the period of study participation, currently pregnant or breastfeeding