Lifestyle and Its Association With Maintaining Health

This study is part of the LIFEHEALTH project and will be conducted in five Mediterranean European Union countries: Croatia, Greece, Italy, Slovenia, and Spain. The study is planned for the first year of the project and aims to assess adults' lifestyle habits and their relationship to physical and mental health.

Each participating country will recruit approximately 500 respondents, selected to provide a representative sample of adults living in Mediterranean regions. Inclusion criteria are: adults aged 18 years or older, residing in the participating country, and willing to complete an online questionnaire. There are no specific exclusion criteria, except inability to provide informed consent or complete the survey.

Data will be collected via an online questionnaire. The survey includes questions about: consumption of the Mediterranean diet, physical activity, sleep habits, stress perception, mental health, social relationships, overall health. The questionnaire will be prepared in English and translated into local languages using the back-translation method to ensure accuracy and consistency. Each country's team will distribute the survey using digital platforms such as email, WhatsApp, and other online tools. Participation is voluntary, and respondents will be informed about the study objectives, procedures, and their rights before completing the questionnaire. Respondents may withdraw at any time without consequence. Before starting the survey, respondents will click the "I Agree" button to show that they understand the study and agree to take part. Statistical analyses will examine relationships between lifestyle factors and self-reported physical and mental health. The analyses will help identify lifestyle habits most strongly associated with health outcomes across countries. The collected data and results interpretation will provide a detailed overview of current lifestyle patterns in Mediterranean populations and its asociations between lifestyle and health outcomes. The findings will inform public health initiatives and support planning of future research aimed at improving health and well-being .

Primary outcomes

• Mediterranean diet adherence [through study completion, an average of 1 year]: Assessed using validated dietary questionnaires to evaluate participants' adherence to Mediterranean diet principles and monitor changes over time. The Mediterranean Dietary Serving Score (MDSS) evaluates 14 food groups, including cereals, fruits, vegetables, olive oil, nuts, dairy, meat, fish, eggs, legumes, potatoes, wine/beer, and sweets. Consumption is rated on a 7-point Likert scale. Scores above 14 indicate regular adherence to a Mediterranean diet.
• Physical Activity [through study completion, an average of 1 year]: Assessed using the Godin Leisure-Time Exercise Questionnaire to evaluate participants' frequency and intensity of physical activity during free time, and to monitor changes in exercise behavior over time. Godin Leisure-Time Exercise Questionnaire (GLTEQ), calculates a total score by multiplying the weekly frequency of strenuous, moderate, and light activities by 9, 5, and 3, respectively. Higher scores indicate greater levels of physical activity and allow monitoring of changes in exercise behavior over time.
• Sleep Hygiene [through study completion, an average of 1 year]: Assessed using validated sleep hygiene questionnaires to evaluate participants' sleep habits, routines, and behaviors that promote restorative sleep. The Sleep Hygiene Index (SHI) consists of 13 items for self-assessment of sleep-related behaviors. Participants rate how often they engage in specific behaviors on a 5-point scale: 0 = never, 1 = rarely, 2 = sometimes, 3 = often, 4 = always. Scores are summed to provide a global sleep hygiene score, with higher scores indicating poorer (maladaptive) sleep hygiene and a greater presence of behaviors that disrupt sleep quality
• Perceived Stress [through study completion, an average of 1 year]: Self-reported questionnaire to assess perceived stress levels. The Perceived Stress Scale-10 (PSS-10) assesses the perception of stressful situations over the past month through 10 items rated on a 0-4 scale. Total scores range from
• Attitudes toward a Healthy Lifestyle [through study completion, an average of 1 year]: The Attitudes toward a Healthy Lifestyle Questionnaire is based on six core domains of lifestyle medicine: balanced nutrition, regular physical activity, effective stress management, sleep quality, quality of interpersonal relationships, and avoidance of risky behaviors such as smoking and alcohol consumption. The instrument consists of 15 items. Responses are recorded using a 5-point Likert scale, where 1 indicates complete disagreement and 5 indicates complete agreement with the statement. Reverse scoring is applied to negatively worded items (items 1, 4, 7, 8, 10, and 12). The total scale score is calculated by summing the responses to all items, resulting in a possible score range from 15 to 75. Higher total scores reflect more positive attitudes toward a healthy lifestyle.
• Healthy Days (Physical and Mental Health) [through study completion, an average of 1 year]: Assessed using the CDC Healthy Days questionnaire to evaluate the number of days in the past 30 days when participants perceived their physical or mental health as not good. The Health Related Quality of Life 14 item measure (CDC HRQOL 14) is a generic self report questionnaire developed by the U.S. Centers for Disease Control and Prevention to assess overall health related quality of life. It comprises 14 items that capture perceived physical and mental health status over the past 30 days, including self rated general health, the number of days with poor physical health, poor mental health, days when health limited usual activities, and additional questions on activity limitations and symptoms such as pain, depression, anxiety, rest, and energy. The measure provides a summary of health related quality of life and has been widely used in public health surveillance, research, and population health studies. Higher scores generally reflect poorer health related quality of life.
• Personal Wellbeing [through study completion, an average of 1 year]: Personal Wellbeing Index (PWI) is self-report measuring subjective well-being across seven domains: standard of living, health, achieving in life, personal relationships, personal safety, community-connectedness, and future security. Each domain is rated on an 11-point Likert scale (0-10), with higher scores indicating greater subjective well-being. The total PWI score is calculated as the mean of the domain scores.

Secondary outcomes

• Association between lifestyle habits and physical health [through study completion, an average of 1 year]: Relationship between lifestyle factors and self-reported physical health status
• Association between lifestyle habits and mental health [through study completion, an average of 1 year]: Relationship between lifestyle factors and self-reported mental health and stress perception.
• Sociodemographic and health-related characteristics [through study completion, an average of 1 year]: Sociodemographic, health, and anthropometric characteristics of respondents across participating countries.
• Associations between lifestyle domains and body mass index. [through study completion, an average of 1 year]: To assess attitudes toward a healthy lifestyle and to explore their relationships with specific lifestyle domains, including nutrition, physical activity, sleep, stress management, interpersonal relationships, sociodemographic characteristics, and body mass index.

Sex: All, ages: 18 Years to any, accepts healthy volunteers

Inclusion Criteria:

* Adults aged 18 years or older
* Residents of participating European countries
* Access to the internet
* Ability to provide informed consent
* Completion of the online questionnaire

Exclusion Criteria:

* Individuals under 18 years of age
* Non-residents of the participating European countries
* Inability to understand the language of the questionnaire
* Cognitive and/or technical difficulties preventing completion of the online questionnaire

• Marija Ljubičić, Principal investigator, University of Zadar, Croatia