Sleep The relationship between sleep quality and nitric oxide in healthy volunteers

Objective: Nitric oxide is a molecule which is synthesized by the oxidation of L-arginine and considered to be effective in the pathophysiology of many diseases such as cardiovascular diseases. The aim of this study is to investigate the effect of expiratory nitric oxide (FENO) levels on the quality of sleep and its relationship with smoking.

Method: Healthy volunteers participated in the study were divided into three groups. The first group consisted of 269 persons who are non-smokers. The second group consisted of 59 volunteers who stopped smoking but smoked for a long time. The third group consisted of 371 volunteers who are current smokers. The Quality of sleep in patients was measured by Pittsburgh sleep quality index, expiratory nitric oxide (FENO) levels were measured by chemiluminescence analyzer (Nioxin-MINO, Aerocrine AB, Stockholm, Sweden).

Results: FENO values of non-smoker group, ex-smoker group, and current smokers group were 24±9 ppb (parts per billion), 23±9 ppb, and 19±8 ppb, respectively. FENO values between the groups were statistically different (p<0,05). There was a negative correlation between FENO levels of population and Pittsburgh sleep quality index scores (r= 0.093). Pittsburgh sleep quality index scores of non-smoker group, ex-smoker group, and current smokers group were 5.17±2.85, 4.68±2.50, and 4.38±2.68, respectively. Pittsburgh sleep quality index scores between the groups were statistically different (p<0,05).

Conclusion: It is known that FENO values are low in patients with OSA and they are normalized after CPAP therapy. However, the relationship between FENO and sleep quality is still not clear in healthy population. Can FENO be the indication of the sustainability of a physiological process rather than a pathological process in sleep disorders? It is interesting that quality index scores of smokers were lower than ex-smokers and nonsmokers group in the study.