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.

Sleep has a recreating, health promotive and regenerative function. Research shows that intensive care patients suffer from sleep deprivation and bad sleep quality with considerable negative consequences. The aim of the report was to examine how much nocturnal sleep patients without ventilator treatment get and to observe factors that may influence sleep. Methods: An observation chart was used to collect data. The staff’s observation of the patients’ night sleep and estimated nocturnal noise- and light levels in the patients’ rooms were documented. The patients’ answers to questions about pain and possible causes for their awakenings were noted. The staff documented also their own perception of what could have awakened the patient, plus the use of ear plugs, sleep medication and sedatives. Results: The results show that patients at CIVA have too short nocturnal sleep. Furthermore their sleep is fragmented and there are few sleep periods of 90 minutes or longer, which means that the sleep structure is disturbed. The results show also that there is room for improvement work at CIVA concerning factors which may influence the patients’ nocturnal sleep. Conclusions: Patients at CIVA have too short and fragmented night sleep. Efforts to promote the patients night sleep should be intensified. / Sömn har en rekreerande, hälsofrämjande och regenererande funktion. Forskning visar att intensivvårdspatienter har sömnbrist och dålig sömnkvalitet med betydande negativa konsekvenser. Rapportens syfte var att kartlägga hur mycket nattsömn icke- ventilatorbehandlade patienter på CIVA får och att observera faktorer som kan påverka sömnen. Metod: Ett formulär användes till datainsamling. Personalens observationer av patientens nattsömn samt skattade nattliga ljud- och ljusnivåer i patientsalen dokumenterades. Patientens svar på frågor om smärta och möjliga orsaker till uppvaknanden noterades. Personalen dokumenterade även sin egen uppfattning om vad som kunde ha väckt patienten samt användning av öronproppar, sömnmedicin och lugnande medicin. Resultat: Resultaten visar att patienterna på CIVA har för kort nattsömn. Dessutom är sömnen fragmenterad och det förekommer få sömnperioder à 90 minuter eller längre vilket betyder att sömnstrukturen är störd. Resultaten visar även att det finns utrymme för förbättringsarbete på CIVA angående faktorer som kan påverka patienternas nattsömn. Slutsats: Patienterna på CIVA har för kort och fragmenterad nattsömn. Kvalitetsutvecklingsarbetet för att främja patienternas nattsömn borde intensifieras.

The primary, descriptive aim of this dissertation was to describe the nighttime sleep quality of previously mechanically ventilated older adult patients within 24-48 hours of transfer out of the intensive care unit (ICU) to a medical-surgical floor. The secondary, exploratory aim was to examine the relationships between post-ICU sleep efficiency (SE) and wake after sleep onset (WASO) with grip strength in previously mechanically ventilated older adult patients within 24-48 hours of transfer out of the ICU. The study included 30 adults ages 65 and older (11 women, 19 men; age 71.37 ± 5.35, range 65-86 years), who were functionally independent at home prior to hospitalization, mechanically ventilated during their ICU stay, and were within 24-48 hours of transfer out of ICU to a medical-surgical floor at Tampa General Hospital, a level 1 trauma center. Subjects wore an actigraph monitor on the dominant wrist (Actiwatch Spectrum) to monitor sleep over two consecutive nights. Parameters of post-ICU sleep quality included total sleep time (TST), sleep efficiency (SE), wake after sleep onset (WASO), sleep latency (SL), and number of awakenings (NA). The outcome measure of motor function was dominant hand grip strength, assessed by the National Institutes of Health Toolbox Motor Battery Grip Strength Test. Sleep data collected between nighttime hours (9:00 PM to 9:00 AM) on both nights were analyzed. For the descriptive aim, means for each sleep parameter and clinical characteristics were reported. For the exploratory aims, multiple regression analyses examined the individual associations between mean sleep parameters (SE and WASO) and grip strength. Study subjects had a mean SE of 63.24 ± 3.88% and spent 135.39 ± 9.94 minutes awake after sleep onset. The mean TST among subjects was 7.55 ± 2.52 hours, ranging from 2.02 to 10.84 hours of sleep, out of the 12 hours of total time in bed. A total of 6 (20%) subjects slept less than 5 hours each night, and a total of 6 (20%) subjects slept greater than 10 hours each night. The mean SL among study subjects was 42.57 minutes, and ranged from 0.0 to 237.75 minutes. Overall, subjects’ average NA was 78.28 ± 26.39, ranging from 35 to 136 awakenings. In multiple regression analysis, SE was significantly and negatively associated with grip strength, after adjusting for potential confounding factors. The model predictors explained 80.8% of the variance in grip strength, [R2 = .808, F(10, 15) = 6.324, p = .001]. Higher SE independently predicted worse grip strength (β = -0.326, p = .036). Further, among the tertiles of subjects with moderate or high TST (sleep duration ≥ 6 hours, n = 23), there remained a significant, negative association between SE and grip strength. The predictors explained 73.7% of the variance in grip strength, [R2 = .737, F(5, 15) = 8.416, p = .001]. Higher SE independently predicted worse grip strength among the subset of subjects with moderate or high sleep duration (β = -0.296, p = .046). Among the two quartiles of subjects with moderate-high or high WASO (≥ 120 minutes spent awake after sleep onset, n = 16), there was a significant, negative association between WASO and grip strength, after adjusting for covariates. The model indicated that the predictors explained 91.4% of the variance in grip strength [R2 = .914, F(6, 8) = 14.134, p = .001]. Greater WASO independently predicted worse grip strength (β = -0.276, p = .04). Finally, the effects of sex and preexisting obstructive sleep apnea (OSA) on grip strength were individually examined. Higher SE independently predicted worse grip strength among male subjects (β = -0.353, p = .039), as did preexisting OSA (β = -0.493, p = .033). In summary, objectively measured sleep quality was disturbed among previously mechanically ventilated, hospitalized older adults, even after transfer out of ICU to a medical-surgical floor. Longer TST and greater SE predicted worse grip strength among these frail patients who were previously independent, community dwelling older adults. Among the subjects with more severely fragmented sleep, WASO also independently predicted weaker grip strength. As poor grip strength is an indicator of ICU-acquired weakness, optimal sleep duration and less sleep disturbances may be crucial in prevention of worse functional outcomes and new institutionalization. Additional research is needed to discern the temporality of associations between sleep quality and motor function among older adult survivors of critical illness.

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