| dc.description.abstract | Longitudinal, cross-sectional, and acute experimental research demonstrate that a short sleep duration is associated with an increased risk of both cardiovascular and cerebrovascular disease. Chronic habitual short sleep duration is associated with an increased dementia risk, however a quarter of the population fail to meet sleep duration guidelines. It is thought that alterations in cerebrovascular function precede symptoms of cognitive decline and dementia. Currently, no evidence exists on measures of cerebrovascular function, such as neurovascular coupling (NVC), and habitual sleep across the lifespan. The association of chronic poor sleep and dementia is likely due to the repeated exposure to a poor night’s sleep. Therefore, there is value in performing controlled, interventional work to understand the acute responses to a single night of sleep restriction. Furthermore, following a night of poor sleep, individuals commonly consume caffeine to increase alertness, but caffeine is known to simultaneously reduce brain blood flow. It is unknown how caffeine affects cerebrovascular function in a sleep restricted state. The purpose of this thesis was therefore to explore 1) the impact of one night of partial sleep restriction on NVC and, 2) whether caffeine ingestion affects NVC after partial sleep restriction in young healthy adults. NVC was determined using transcranial Doppler ultrasound (TCD) to measure blood velocity through the posterior cerebral artery (PCAv) during a visual search task. TCD was also used to measure blood velocity through the middle cerebral artery (MCAv) during cognitive function tests, both of which were assessed before and after normal sleep and partial sleep restriction, and following caffeine ingestion. This study found that NVC was unaltered following partial sleep restriction, and that the magnitude of the NVC response was unchanged after caffeine ingestion in both the rested and sleep restricted state. However, both absolute PCAv and MCAv were lower after caffeine, though this response did not differ between normal and restricted sleep. This study was the first to examine the effects of partial sleep restriction and subsequent caffeine ingestion on a measure of cerebrovascular function. However, sleep restriction was only studied in the form of a 50% sleep restriction, with sleep taking place in the second half of the night. Future research should explore whether the relationship between sleep and NVC is dependent on how sleep is accrued throughout the night, for example fragmented/broken sleep. | en_GB |
