Diurnal naps and sleep interruption as precipitating factors of sleep paralysis in elite Japanese athletes

Abstract

Abstract Background Sleep paralysis and hypnagogic hallucinations are observed during sleep-onset rapid eye movement (REM) periods (SOREMPs). SOREMPs are associated with sleep pattern disruption. This study aimed to assess the occurrence of sleep paralysis and several sleep parameters in elite athletes and control groups to determine the relationship between sleep paralysis and specific sleep characteristics.Methods Eighty-four (47 male) elite and 116 (49 male) non-athletes (controls) were recruited. A questionnaire regarding the occurrence of sleep paralysis and several sleep parameters was administered.Results A relationship between sleep paralysis and long diurnal nap frequency was revealed. A small proportion (6.5%) of participants with sleep paralysis did not routinely take long naps, while 24.3% of those without sleep paralysis did not routinely take long naps. This proportion was rather striking in athletes compared with that in non-athletes. Participants with sleep paralysis experienced more frequent sleep interruptions than those without sleep paralysis, a difference that was more pronounced in athletes than in non-athletes.Conclusion The prevalence of sleep paralysis was reported to be high among elite Japanese athletes and non-athletes, a finding that is in accordance with previous reports. Long nap routines and sleep interruptions are closely associated with sleep paralysis, especially in elite athletes. A lengthy nap routine is sometimes recommended for sleep loss compensation, especially among elite athletes; however, since the occurrence of sleep paralysis may be a sign of sleep-wake rhythm disruption, caution is suggested when recommending long nap routines, even to athletes.