Impact of Exercise‐Induced Dehydration on Perceived Sleep Quality
Authors: Adams William M. , Vandermark Lesley W. , Belval Luke N. , Benjamin Courteney L. , Giersch Gabrielle E.W. , Katch Rachel K. , Lee Elaine C. , Armstrong Lawrence E. , DiStefano Lindsay J. , Casa Douglas J. 
Published: June 2021

ObjectiveTo examine the effect of exercise‐induced dehydration on perceived sleep quality.MethodsTwenty‐three recreationally active males (mean±SD; age, 21±2 y; height, 179.8±6.4 cm; body mass, 75.18±8.09 kg; VO2max, 51.7±5.5 ml•kg−1•min−1; body fat, 14.4±4.6%) completed three randomized exercise trials: euhydrated + fluid replacement during exercise (EUR), euhydrated + no fluid replacement during exercise (EUD), and hypohydrated arrival via fluid restriction + no fluid replacement during exercise (HYPO) in hot conditions (ambient temperature, 35.3±0.6°C; relative humidity, 31.3±2.0%). Twenty‐four hours prior to (PRE24) and following (POST24) the exercise trial, a nude body mass (NBM) was recorded, and participants collected all urine in a sealed container to assess 24 h hydration status via urine osmolality (UOSMO) and percent body mass loss (%BML). Prior to exercise (PREEX) and following exercise (POSTEX), NBM was measured to calculate %BML. At PREEX and POST24 participants completed the Karolinska Sleep Diary (KSD) to obtain measures of overall perceived sleep quality (KSDTOT) from the previous night's sleep. Time spent sleeping (SLTM), sleep efficiency (SLEFF), overall sleep quality (SLQUAL), and total number of awakenings (AWTOT) was were also reported. Trial x time repeated measures ANOVAs with a Tukey post hoc test were used to evaluate differences in continuous dependent variables with significance set a priori p<0.05.ResultsAt PRE24, UOSMO was significantly different (p<0.05) in HYPO (605±212 mOsm•kg−1) versus EUD (441±176 mOsm•kg−1), and EUR (411±207 mOsm•kg−1). %BML was significantly greater (p<0.001) in HYPO at PREEX (1.3±1.2%) and POSTEX (5.0±0.9%) versus EUD (−0.9±1.0%, 3.4±1.0%) and EUR (−0.8±1.0%, 0.2±1.0%). %BML in EUD was significantly greater than EUR at POSTEX, p<0.001. At POST24, UOSMO was significantly higher (p=0.002) in HYPO (714±292 mOsm•kg−1) versus EUR (443±158 mOsm•kg−1); however, no significant differences (p>0.05) were observed in %BML (HYPO, 0.3± 1.3%; EUD, −0.3± 0.9%; EUR, −0.0±1.1%). Hypohydration achieved prior to (PREEX) and following (POSTEX) exercise did not influence KSDTOT, SLTM, SLEFF, SLQUAL, KSDTOT, or AWTOT (p>0.05). Independent of trial, SLTM (MD [95%CI], 34.6 min [7.7, 61.5], p=0.012) and SLEFF (1.4% [0.6, 2.78], p=0.041) were significantly greater at POST24 versus PREEX.ConclusionsFollowing exercise in hot conditions, participants reported an increased length and more efficient bout of sleep. The ability of participants to return to within ±1% of baseline body mass within 24 h may have negated any adverse effects of hydration state on perceived sleep quality, however future research is needed to investigate the effects of sustained hypohydration on sleep quality.Support or Funding InformationThis study was funded in part by Halo Wearables, LLC and General Electric.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.