Efficacy of Dietary Supplementation With Melatonin in Targeting Sleep Quality

Inclusion criteria: * subject Informed consent form (ICF) is signed * aged 24-65 years at the time of the signature of ICF * suboptimal sleep quality according to Pittsburgh Sleep Quality Index (PSQI-SI): PSQI higher than 5 * no clinically significant (subthreshold) insomnia according to Pittsburgh Sleep Quality Index (PSQI-SI) (Kmetec et al., 2022): PSQI up to 9 * a body mass index (BMI) up to 32 kg/m2 * stable medications for non excluded concurrent medical conditions for six weeks prior to the screening visit * ability to ingest oral food supplement (study product) * willing to follow all study procedures, including attending all site visits and use of actigraphy Exclusion criteria: * diagnosed or subject to therapy due to sleep disorders * acute infectious disease * any kind of chronic pharmacological therapy with antihypertensives or antidepressants * any kind of other pharmacological therapy that could interact with active ingredients used in the study * pregnancy or planned pregnancy, lactation, menopause (with clinically relevant symptoms/therapy) * use of beta-blockers * chronic use of use of prostaglandin synthesis inhibitors (nonsteroidal anti-inflammatory drugs), such as acetylsalicylic acid and ibuprofen * supplementation with melatonin or other food supplements intendent for sleep quality during last 2 weeks * unwillingness to maintain caffeine abstinence after 4:00 PM during the study * not having a mobile upper extremity for attaching an actigraph * known alcohol and/or drug abuse * unwillingness to comply with the maximum limit of 2 alcoholic drinks per day, and only up to 1 alcoholic drink after 6:00 PM during the study * known lactose/gluten intolerances/food allergies * known gastrointestinal disease * less than 5 years after treatment for gastrointestinal cancer (stomach, duodenum or colon) * have stomach or bowel resection * night work (including as part of shift work) * mental incapacity that precludes adequate understanding or cooperation * participation in another investigational study