Influence of the Sleep and Chronotype Pattern in Metabolic, Anthropometric and Biochemical Responses in Patients Submitted to Bariatric Surgery
Conditions: Bariatric Surgery Candidate
Sponsor: Federal University of Uberlandia

 
Title: Influence of the Sleep Pattern in Patients Submitted to Bariatric Surgery 
NCT number: 03485352 
Date: 03/04/2021 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Study protocol Participants and ethics 
This longitudinal and observational study was performed with patients eligible for 
bariatric surgery in a private clinic in Uberlandia, Minas Gerais, Brazil, between June 
2017 and April 2018. The inclusion criteria were patients in the preoperative period of 
bariatric surgery aged between 18 and 59 years, body mass index (BMI) ≥ 35 kg/m² 
associated with two comorbidities or BMI > 40 kg/m² independent of comorbidities, 
and who would undergo Roux-en-Y gastric bypass or sleeve gastrectomy. 
 The exclusion criteria were patients who would undergo revisional surgery. The study 
was approved by the Human Research Ethics Committee (66023717.8.0000.5152), and 
all volunteers signed an informed consent form. The sample size required was 
determined using the G*Power software version 3.1. 
 The sample size calculations were based on f test linear ANOVA, with effect size of 
0.15, an alpha level of 0.05, 95% power, repeated measures, within between 
interactions. Given these specifications, a total sample of 116 patients was required.  
Follow-up evaluations 
An initial questionnaire including socio-demographic and general information was 
applied in the preoperative period. Sleep and anthropometric pattern and food 
consumption were evaluated at the baseline, third and sixth months after surgery. 
Biochemical parameters were assessed at baseline and in the sixth month.  
Sleep patterns and SJL The sleep pattern was determined by applying a questionnaire 
with questions: "What time do you usually go to sleep during the week?"; "How long 
(min) do you stay up in bed before sleep onset (after turning off the lights) during the 
week?"; "What time do you usually wake up during the week?"; "What time do you 
usually go to sleep on weekends?"; "How long (min) do you stay up in bed before sleep 
onset (after turning off the lights) on weekends?"; "What time do you usually wake up 
on weekends?". The bedtime on weekdays and at weekends was obtained whereas 
the time taken to fall asleep. SJL was calculated by the absolute difference between 
the mid-sleep time on work-free days and the mid-sleep time on work-days.  
Anthropometric variables  
The weight, height, waist circumference, hip circumference and neck circumference 
were measured by standardized methods at all evaluation appointments. The BMI was 
calculated and classified according to the recommended age ranges for adults (20 
years < age < 60 years). Standardized cutoffs were used for waist circumference and 
neck circumference.  
 

Metabolic profile  
Serum levels of fasting glycaemia, fasting insulin, total cholesterol (TC), high density 
lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL) 
and triglycerides (TG) were assessed to evaluate the metabolic profile. The blood 
samples were collected after a 12-h fasting period. All analyses were performed 
according to validated methodologies. 
Dietary Intake Data 
 The food consumption was evaluated by two 24-h recalls (24HR) at each evaluation 
moment (baseline, third and sixth month), with one occurring on a weekday (applied in 
a private room with the interviewer and participant only) and the other one on the 
weekend (applied by phone, as done in previous studies) . Both 24HRs were conducted 
by a trained nutritionist using the multiple-pass method. Energy, macronutrients and 
fiber data were assessed using the software Dietpro Clínico 5.0. Six 24HRs were 
collected in total, and the mean of the week and weekend 24HRs was used for each of 
the three evaluation moments.