Inappropriate sleep time trajectories from adolescence to early adulthood: an analysis from a Brazilian birth cohort

Abstract

Background: inappropriate sleep time has been related to negative health outcomes and chronic diseases.

Aim: to determine groups for inappropriate sleep time trajectories during adolescence to early adulthood and characterize them in the Pelotas 1993 Birth Cohort, Brazil.

Methods: sleep time were recorded in the follow up visits at ages 11, 18 and 22 years old. The sleep time was obtained subtracting the time when the individual went to bed and the time of wake up. Inappropriate sleep time was defined as <7 and >12 hours at age 11 and <6 and >11 at ages 18 and 22 year. Trajectories were obtained from generalized linear models with several options tested through the routine “traj” in Stata software.

Results: from de 5249 original cohort members, we analyzed 3395 individuals. The model with best fit was a four-group model for inappropriate sleep time, named as: quick increase, then maintenance (27.0%); slow increase, then slow decrease (35.3%); slow decrease, starting with intermediate proportion (10.8%;) and slow decrease, starting with high proportion (26.9%). There were differences among the groups regarding sex (57% of females in the group slow decrease, starting with high proportion, p=0.002), overweight/obesity (33% in the group slow decrease, starting with intermediate proportion, p=0.041), wheezing in past 12 months at ages 18 (p=0.005), and 22 years (p=0.018) higher in the group slow decrease, starting with high proportion (14% and 12% respectively).

Conclusions: four groups of modelled based trajectories were identified with different patterns. There were important differences in biological, behavioral and clinical characteristics among these groups.