Effects of controlled dehydration on sleep quality and quantity: A polysomnographic study in healthy young adults

Dehydration is associated with several alternations in body homeostasis involving both physiological and mental aspects. In addition some studies have reported a negative effect of dehydration on subjectively assessed sleep-related parameters. The aim of the current study was to examine for the first time the effect of controlled dehydration on sleep quality and quantity using the gold-standard method of polysomnography. Twelve healthy male volunteers participated in this study (23.4 ± 0.8 years). Participants performed an in-house full polysomnographic assessment in two different occasions taking place in random order: (i) in a dehydrated state; and (ii) in a euhydrated state. In the dehydration scenario, the participants were allowed to consume only 1.25 L of non-caffeinated fluids, while during the euhydrated state participants had to drink at least 3 L of non-caffeinated fluids during the last 24 hr before the polysomnographic study. Urine specific gravity was assessed by refractrometry on collection day in order to assess hydration status. Participants who did not fulfil the hydration criteria were rescheduled. All participants successfully completed the two polysomnographic studies without any complaints or adverse effects reported. No significant differences were found in any of the examined indices of sleep quality and quantity between the dehydration and euhydration scenarios (p > .05). This is the first study to show that controlled mild dehydration does not seem to affect sleep quality and quantity in young healthy adults. More research is necessary to further verify these conclusions and assess whether other parameters are involved in the manifestation of sleep disturbances.