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Título

Sleep-wake cycle pattern in blind people living in low latitude areas (Natal-RN-Brazil)

Resumo

INTRODUCTION: It is present in the current literature that blind individuals have sleep disorders related to circadian rhythmicity. These studies have been guiding, on a global, scale therapeutic approaches aimed at the blind. However, such studies were carried out in high latitude regions, so it is necessary to evaluate the pattern of the sleep-wake cycle in blind people in low latitude areas, with little variation in the photoperiod. OBJECTIVE: Characterize sleep and rhythm of rest activity in blind people living in a low latitude region (Natal/RN). METHODS: Participated in the study 19 total blindness people, living in the city of Natal. The parameters of the sleep-wake cycle were characterized by the actimetry technique (Actrust - Condor Instruments) that was used for 20 days. The analyses were done in the ActStudio software and were quantified sleep parameters and non-parametric variables of the rhythm of activity and rest (IV = intraday variability; IS = interday stability; M10 = 10 hours of higher activity; L5 = five hours of lower activity and RA = relative amplitude). 3 participants were excluded due misuse of the actimeter. Project was approved by CEP - UFRN. RESULTS: The blind volunteers in this study had a sleep duration of 377.7min (6.28 hours) ± 42 min, a sleep latency of 6 ± 11 min and an average sleep efficiency of 84.8% ± 6.1%. We found that 68% of volunteers have a sleep time recommended by the National Sleep Foundation (NSF), 12.5% have adequate sleep and 18% have sleep deficit. The time to go to bed was 23:30 ± 98 min and the time to get up was 7:24 ± 102 min. For the non-parametric variables of the rhythm of activity and rest, an average of IV of 0.72 ± 0.18 and the SI of 0.4 ± 0.09 were found. This shows that the blind subjects presented a little fragmented sleep and low stability of the circadian rhythm. The average value of M10 was 124 ± 46, starting at 08:11 min ± 123 min and for L5 17.3 ± 8, starting at 02:25 ± 118 min. The AR value of 0.64 ± 0.3. CONCLUSION: The majority (68%) of blinds in our study had a sleep duration and a sleep efficiency above 85%. The subjects expressed a nocturnal sleep pattern, as observed by L5 and M10 value and interval, signaling an absence of desynchronization and suggesting a greater influence of non-photic factors on synchronization. Thus, further studies are needed to evaluate which and how these non-photic factors are synchronizing the sleep-wake cycle.

Palavras Chave

Sleep, circadian, blindness, low latitude