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The use of the actigraphy in the assessment of the sleep-wake cycle according to body mass index: preliminar results.


The actigraphy records events during the sleep-wake cycle.


To describe the characteristics of the sleep-wake cycles by actigraphy in the participants with different body mass indexes (BMI).


This is a cross-sectional and descriptive study. A convenience sample of 15 participants was selected, nine females and six males, age range from 25-34 years (28.5±2.6). BMI was obtained and the participants were classified: normal weight (n=5), overweight (n=5) and obese (n=5). After, the participants were instructed to maintain their usual lifestyle and was instructed to use the actigraph in the non-dominant wrist (ActTrust®) during four days and three consecutive nights. Sleep variables were obtained by actigraphic analysis and from subjective sleep diary. The variables were: latency period, wake after sleep onset (WASO), number of awakenings, distal skin temperature (DST), mean value of 5 continuous hours of lowest activity (L5) and mean value of 10 continuous hours of highest activity (M10). Descriptive analysis was performed consisting of frequencies, arithmetic means and standard deviations.


The results of sleep performance by actigraphy showed that the latency period was 100±0.17’ in the overweight and obesity groups, and 52±0.10' in normal weight group, indicating difficulty in initiating sleep in all groups. Higher WASO values were observed in the obesity group (99±0.40') and low in the overweight and normal group 47±0.24' and 42±0.28', respectively. A higher number of awakenings was observed in the obesity group (15±8), compared to the overweight (9±5) and control groups (9±7). DST values ranged from 33°-34°C in the period from 02:20 to 04:30 for all groups, indicating the degree of skin vasodilation. Low M10 values indicated low activity during wakefulness observed in the obese group (16:59±01:24h), when compared to the normal weight group (17:02±07:43h). Low L5 values indicated low awakening sleep and less fragmented sleep in the normal weight group (01:01±00:20h). The increase in the value of L5 indicated the presence of awakenings during sleep, suggesting fragmented and short sleep, as observed in the overweight (02:39±00:20h) and obesity (03:01±00:31h) groups.


Given the results obtained, it can be concluded that, the obesity group showed low physical activity, higher number of awakenings and fragmented sleep, when compared to the normal weight group, which presented acceptable activity, fewer arousals and less fragmented sleep.


Sleep, obesity, actigraphy


Área Clínica


Universidade Estadual de Campinas - Sao Paulo - Brasil


Dora Zulema Romero Díaz, Maria Beatriz Duarte Gavião