Poor Sleep Associated with Clinically Severe Obesity Is Independent of OSA Status

Obesity has been reported to be associated with short sleep duration. It follows that patients with a BMI >35kg/m² could be expected to have the poorest sleep. This poor sleep could be explained by the presence of obstructive sleep apnoea (OSA), although treatment with positive airway pressure (PAP) may modify this. The purpose of this study is to determine if patients attending for bariatric surgery have poor sleep independent of OSA status.

Sleep duration and quality, using the Pittsburgh Sleep Quality Index (PSQI), was analysed in 203 patients undergoing bariatric surgery between June 2016 and May 2019 in a single centre. Anthropometric data on all patients were recorded as well as presence of OSA and PAP usage.

The bariatric population reported an average (standard deviation) sleep duration of 6.5 (1.6) h, and 67.9% of patients had a documented poor sleep quality (PSQI>5). The presence of OSA did not significantly influence either sleep duration (p=0.23) or sleep quality (p=0.5). On logistic regression, there was no significant relationship between sleep duration or sleep quality and the following variables: age, sex, and AHI. There was however a significant association between BMI and sleep quality (p= 0.007). PSQI was inversely associated with BMI. This equated to 1 kg/m² weight gain being associated with 0.097 decrease in PSQI score.

The presence of OSA does not influence either sleep duration or sleep quality in the bariatric surgical population. This suggests that clinically severe obesity itself may cause poor sleep.