Abstracts

P6 The effects of partial sleep restriction and subsequent caffeine ingestion on neurovascular coupling in young healthy adults

Abstract

Habitual poor sleep is associated with cerebrovascular disease, and acute total sleep deprivation alters the ability to match brain blood flow to metabolism (neurovascular coupling, NVC) though it is not known how partial sleep restriction affects NVC. Furthermore, caffeine disrupts NVC in the rested state, but its effects in the sleep restricted state are unknown. The purpose of this study was therefore to investigate the effects of partial sleep restriction and subsequent caffeine ingestion on NVC.

Seventeen healthy adults (age 27 ± 5 years, 9 female) completed three separate overnight experimental conditions with morning supplementation: normal sleep plus placebo (Norm_Pl), normal sleep plus caffeine (Norm_Caf), and partial (50%) sleep restriction plus caffeine (PSR). PSR involved participants staying awake during the first half of the night and waking at their normal wake time. Participants completed a visual search induced NVC assessment, with posterior cerebral artery blood velocity (PCAv) measured using transcranial Doppler ultrasound. NVC was assessed the evening before and twice the morning after each sleep condition – pre and 1 hour post caffeine ingestion.

NVC responses as a percent increase from baseline and as incremental AUC were not significantly different at any timepoint, across all conditions (P > 0.87). PCAv at baseline, peak, during the final 10 seconds of the visual search task, and as total area under the curve (AUC) were significantly lower 1 hour after caffeine ingestion in both the Norm_Caf and PSR conditions as compared to post placebo in Norm_Pl (P < 0.05), with no difference between Norm_Caf and PSR (P > 0.14).

In conclusion, NVC was unaltered after partial sleep restriction, and caffeine did not modify the magnitude of the NVC response in either the rested or sleep deprived state. Future research should explore how an accumulation of habitual poor sleep affects cerebrovascular function.

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