BACKGROUND: Current research regarding the impact aging has on characteristics of sleep suggest that over the course of one’s lifespan, the quantity and quality of sleep declines. Sleep quality is a measure of the extent to which sleep is consolidated- the less number of brief awakenings one experiences during a period of sleep, the better. The extent to which degradation of sleep quality may impact overall health and increase susceptibility to age-related diseases is currently unknown, nor is the mechanism that mediates sleep fragmentation and consolidation understood.
OBJECTIVE: The purpose of this study was to ascertain if the increased sleep fragmentation experienced with age is due to a decreased arousal threshold towards external stimuli. A decreased ability to inhibit sensory processes during sleep could potentially trigger a greater number of brief awakenings and negatively impact sleep quality.
METHODS: Various age groups of inbred wild-type genotypes of Drosophila melanogaster had arousal threshold tested during the night using mechanical stimuli to see if the older flies were more likely to be woken up. Sleep characteristics at baseline and after the arousal assay were compared to observe any impacts aging has on the ability to recover from a mild sleep deprivation as such.
RESULTS: I observed an increase in arousal threshold with age; older flies were less likely to be aroused by the presentation of the mechanical stimulus. Arousal threshold findings were consistent between sexes but not between genotypes. It was noted that the degree to which aging impacted arousal threshold was affected by the expected lifespan of a genotype. In terms of sleep characteristics measured outside of the arousal assay, I noticed an increase in quantity of sleep and decrease in activity as flies aged, including a greater reliance on day sleep. This was further reflected by a decrease in rebound sleep after the arousal assay was performed. More specific sleep architecture characteristics such as bout number and bout length were greatly impacted by both sex and genotype.
CONCLUSION: Our results were greatly unexpected in comparison to previous studies, especially in regards to older flies having an increased arousal threshold and an increased quantity of sleep. This is not conclusive, however, as previous studies have shown that the saliency of the stimulus presented may prove important, especially when considering the internal state of the fly. Instead of solely focusing on if older flies are more or less easy to wake up with the application of an external stimulus, it may instead be beneficial to also consider their ability to discriminate between salient stimuli while quiescent.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/48354 |
| Date | 06 March 2024 |
| Creators | Nicholson, Joan |
| Contributors | Bragdon, Beth |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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