Association Between Sleep Quality and Grip Strength Among Young Adults Aged 18–25 Years: A Cross-Sectional Study

Background: Sleep is a critical physiological process that is important for the maintenance of optimal physical, psychological, endocrine and metabolic health. Good quality sleep is vital for cognitive function, tissue repair, immune competence, hormonal regulation and musculoskeletal recovery. The present lifestyle changes such as prolonged screen use, academic stress, irregular sleep timings and the increasing psychosocial stress have led to a significant increase in sleep disturbances among young adults. Poor sleep quality is identified as a major public health problem worldwide and has been associated with impaired attention, reduced academic performance, obesity, cardiovascular diseases, diabetes mellitus, depression and decreased quality of life. Moreover, there is emerging evidence to suggest that inadequate sleep may negatively impact skeletal muscle metabolism, muscle protein synthesis, neuromuscular coordination and physical performance. Handgrip strength is considered as an objective marker of general muscle strength and functional capacity. It is easy, inexpensive, reproducible and has been widely used as a surrogate marker of nutritional status, sarcopenia, frailty and future morbidity. Although many studies have investigated the association between sleep quality and muscle strength in middle-aged and elderly people, there is limited evidence for the association in healthy young adults. Moreover, previous studies presented inconsistent results and it is important to evaluate if sleep quality is a significant factor on muscle strength in this age group. The objective is to find out the correlation between sleep quality and handgrip strength among healthy young adults in the age group of 18-25 years. Material and Methods: The study was observational and cross-sectional and involved a sample of 130 healthy young adults between the ages of 18 and 25 years. Sleep quality was evaluated with the validated Pittsburgh Sleep Quality Index (PSQI) and handgrip strength was evaluated with a calibrated handgrip dynamometer. Anthropometric measurements such as age, height, weight and body mass index (BMI) were measured using standard procedures. The characteristics of the participants were summarized using descriptive statistics. Associations between PSQI score, sleep duration, sleep efficiency and grip strength were evaluated using Pearson correlation analysis. Grip strength was compared using independent sample t-tests between participants with good sleep quality (PSQI ≤5) and those with poor sleep quality (PSQI >5). Statistical significance was set at p<0.05. Results: The average age of the participants was 20.51 ± 1.49 years. The study population consisted of 83 males (63.8%) and 47 females (36.2%). Sleep quality was generally poor among participants, with a mean PSQI score of 6.11±2.72. Poor sleep quality was reported by more than half of the study population (53.8%). The mean grip strength was 30.01±10.89 kg. Pearson correlation analysis showed a weak negative correlation between PSQI score and grip strength (r = –0.058, p = 0.511), indicating that poorer sleep quality was more likely to be associated with lower grip strength, but the association was statistically insignificant. Sleep duration (r = 0.003, p = 0.971) and sleep efficiency (r = 0.052, p = 0.556) did not show any statistically significant relationship with grip strength. The mean grip strength in those with poor sleep quality was lower than good sleepers (29.62 kg vs. 30.46 kg) but this difference was not statistically significant. Conclusion: Poor sleep quality was very common among healthy young adults. Participants with poorer sleep quality had marginally lower grip strength, but we did not find statistically significant association between sleep quality and handgrip strength. These results may indicate that muscle strength in healthy young adults can be explained by various physiological and lifestyle factors, not only sleep quality. Further multicentric prospective studies with objective sleep assessment techniques are warranted to elucidate this relationship.

Keywords: Sleep quality, Pittsburgh Sleep Quality Index, Handgrip strength, Young adults, Muscle strength, Sleep efficiency, Cross-sectional study.