Dehydration during sleep affects cognitive performance

Abstract

To the Editor, We read with interest the response by Drs. Thornton and Trabalon to our recent article, ‘‘Cognitive and academic functions are impaired in children with all severities of sleep-disordered breathing,’’ published in Sleep Medicine 12:489–496, 2011. Their suggestion that dehydration caused by mouth breathing in children with sleep disordered breathing (SDB) is the underlying mechanism for the impairments that we and others have observed is novel. Our findings of impairment in cognition and academic performance are in keeping with those of numerous other researchers [1–9]. It has been hypothesised that these deficits are at least in part due to disruption to sleep and/or repeated hypoxic episodes which are a feature of SDB [10]. In our study, we did not observe any significant sleep disruption using either conventional measures of measurement or spectral analysis of the EEG [11]. In addition, we observed significant impairments in children with primary snoring in the absence of any hypoxic episodes. Thus there must be other mechanisms involved. The idea that this may be dehydration is novel and was not tested in either our study or those carried out previously. To confirm this possibility, further studies would need to be carried out.