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Sleep debit, psychomotor and postural performance decline in Brazilian bus drivers


Sleep debit has been investigated in several populations because it causes behavioral and physiological changes in humans. As well as, it is speculated that the sleep debt can alter the psychomotor and postural performance of nocturnal workers and with that promote a reduction of their productivity and lead to fatigue and still cause accidents at work.


Is there correlation among sleep debt, time awake and worker’s psychomotor and postural performance?


Seventeen night workers (17 bus drivers) were included in the study. The participants worked eight-hours in a 5-consecutive-night system, with two days off. All of them were the male gender, sedentary, and were aged between 25 and 59 years. The measurements were performed over five days. On the first day of protocol, body mass and height were measured, and an actigraph was placed on the wrist of each participant and they wore it for four days. The total sleep time (TST), the time awake (TA), presence of naps during night shift, and the sleep efficiency were measurement by actigraph. On the fourth day of protocol, before and after the night shift (fourth and fifth days: 09:00-10:00 p.m. and 09:00-10:00 a.m.), the psychomotor and postural performance of the participants were recordings by 10-minute Psychomotor Vigilance Task (PVT) and by 30-seconds force platform with eyes-opened, respectively. Pearson’s correlation coefficient was used to calculate the correlation between the sleep-wake parameters (TST and TA), and the psychomotor and postural performance variables: mean reaction time (RT), number of lapses of attention, mean sway amplitude (MSA), and mean sway perimeter (MSP) of center of pressure (COP). The α-level for all analysis was set at 0.05.


The study sample consisted of the 17 male drivers, with a mean age of 40.1 ± 8.1 years and a mean BMI of 27.8 ± 4.8 kg/m2. The mean total sleep time (TST) before the night shift was 291.9 ± 126.7 minutes, and the sleep efficiency was 97.9 ± 1.37%. The mean time awake after the night shift was 877.0 ± 273.9 minutes. The correlations of TTS and TA for the variables related to psychomotor and postural performance are present in the tables 1 and 2.


Sleep debt or long time awake increased postural sway and reduced psychomotor performance of night workers, causing attention and vigilance decline, as well as risks of falls and occupational accidents. Acknowledgment: CEPE, CEMSA, AFIP, CAPES, CNPq, FAPESP.


Sleep debit, Bus driver, Psychomotor performance, Postural performance.


Área Clínica


Universidade Cruzeiro do Sul - Sao Paulo - Brasil, Universidade Federal de Minas Gerais - Minas Gerais - Brasil, Universidade Federal de São Paulo - Sao Paulo - Brasil


Fernanda Narciso, Andressa Silva, José Angelo Barela, Sandra Queiroz, Adriana Carvalho, Stefane Aguiar, Sergio Tufik, Marco Tulio De Mello