Adolescence (ages 10-19) is a critical developmental stage in which individuals undergo significant physical, psychological, and social changes. Health behaviors acquired during this period often persist into adulthood, directly influencing both individual and public health. Adolescents' lifestyles are shaped by factors such as family, school, peers, and socio-cultural environment. A healthy lifestyle includes habits such as regular physical activity, balanced nutrition, adequate sleep, and limited screen time, all of which are key determinants of quality of life.

The aim of this study is to evaluate the effectiveness of an educational program designed to improve high school students' hygiene, screen use, nutrition, physical activity, and sleep habits. It is hypothesized that the program will increase students' healthy lifestyle beliefs and hygiene behaviors, while reducing screen addiction and insomnia levels.

Adolescence, defined by the World Health Organization as the period between 10 and 19 years of age, represents a transitional stage from childhood to adulthood characterized by profound physiological, cognitive, psychological, and social changes. These transformations significantly influence adolescents' health-related quality of life, which is a multidimensional construct encompassing physical, psychological, and social well-being. Health behaviors acquired during this developmental stage tend to persist into adulthood and therefore play a critical role in the prevention of chronic diseases and the promotion of lifelong health. For instance, unhealthy dietary patterns, sedentary lifestyles, excessive screen use, and irregular sleep habits established during adolescence may increase the risk of obesity, cardiometabolic disorders, and psychological problems in later life. Conversely, adopting positive health practices such as balanced nutrition, regular physical activity, proper sleep hygiene, and limited screen time during this period can enhance quality of life and support healthy growth and development.

Adolescents' health behaviors are influenced by multiple environmental factors, including family, peers, school, socioeconomic status, and cultural context. Thus, interventions aimed at promoting healthy lifestyles in this age group require a holistic and multifactorial approach. Education programs focusing on health-related knowledge and practices have been shown to play a key role in shaping positive behaviors and raising awareness about health protection and disease prevention.

The present study aims to evaluate the effectiveness of an educational program designed for high school students, addressing five key domains: hygiene, screen dependency, nutrition, physical activity, and sleep habits. The program seeks not only to increase adolescents' knowledge in these areas but also to instill sustainable health-promoting behaviors. Four hypotheses were established: (1) students in the intervention group will report higher scores on the Healthy Lifestyle Beliefs Scale compared to the control group; (2) their Screen Dependency Scale scores will decrease; (3) their Hygiene Behaviors Scale scores will increase; and (4) their Bergen Insomnia Scale scores will decrease following the program.

This research emphasizes the importance of implementing structured, school-based educational interventions to promote healthier lifestyles among adolescents. By targeting multiple dimensions of health simultaneously, such interventions may contribute to reducing long-term health risks, improving well-being, and fostering healthier future generations.

Inclusion criteria:

• Being a 9th, 10th, or 11th-grade student
• Not having any illness that could cause communication problems
• Volunteering to participate in the study

Exclusion criteria:

-Students who did not meet the inclusion criteria were excluded from the study.