Socio-Demographic, Nutritional, and Lifestyle Factors Influencing Perceived Sleep Quality in Spain, with a Particular Focus on Women and Young People

<b>Objectives:</b> This study examines the relationship between nutrition, lifestyle habits, and perceived sleep quality in a cross-sectional analysis of 22,181 Spanish adults. <b>Methods:</b> Data were collected between August 2020 and November 2021 using the Nutritional and Social Healthy Habits (NutSo-HH) questionnaire, which assessed variables such as sleep duration, self-perceived restfulness, dietary patterns, and physical activity. <b>Results:</b> Findings indicate that 48.9% of participants sleep 7-8 h per night, while 8.6% sleep less than 6 h. Approximately 50% report frequently feeling rested, whereas 45.4% seldom or sometimes feel rested. Non-parametric Mann-Whitney and Kruskal-Wallis tests with Dwass-Steel-Critchlow-Fligner (DSCF) correction revealed that perceived sleep quality had an average score of 3.39 on a 0-5 scale, with significant differences based on socio-demographic and lifestyle factors (<i>p</i> < 0.001 for sex, age, education, income, and living in a family). Participants with sufficient sleep reported a lower BMI, a higher nutritional index, and more weekly physical activity. A network analysis demonstrated strong clustering between sleep variables and eating behaviors. Although causality cannot be established in this observational study, the results suggest that better sleep is associated with the lower consumption of sugary drinks and ultra-processed foods, as well as improved body image and mental health. <b>Conclusions:</b> These findings highlight the interconnectedness of sleep, nutrition, and lifestyle habits, suggesting that targeted interventions in any of these areas could positively influence the others, ultimately improving overall health outcomes.