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- Creators: School of Life Sciences
Sleep is imperative for health and wellness with direct impacts on brain function, physiology, emotional well-being, performance and safety when compromised. Adolescents and young adults are increasingly affected by factors affecting the maintenance of regular sleep schedules. College and university students are a potentially vulnerable population to sleep deprivation and sleep insufficiency. Possible factors that could contribute to poor sleep hygiene include, but are not limited to, academic pressures, social activities, and increased screen time. Arguably, students are still experiencing bone mineralization, until the age of 30 or even 40 years old, which makes it more important to understand the effects that altered sleep patterns could have on continued development of bone health. It is our understanding that to date, studies assessing the risk of sleep insufficiency on bone mineral density in college students have not been conducted. We hypothesized that college-aged students, between the ages of 18-25 years, with shorter sleep durations, greater sleep schedule variability, and poorer sleep environments will have significantly lower bone mineral density. ActiGraph monitoring, via a wrist ActiWatch was used to quantitatively measure sleep habits for up to 7 consecutive days. During the week-long study participants also captured their self-reported sleep data through the use of a sleep diary. Participants were measured one time within the study for bone mineral density of the lumbar spine and total hip through a dual energy x-ray absorptiometry. This was a preliminary analysis of a larger cross-sectional analysis looked at 17 participants, of which there were 14 females and 3 males, (n=5, 1 and 11 Hispanic, Black and White, respectively). The mean age of participants was 20.8±1.7 y with an average BMI of 22.9±3.2 kg/m2. ActiWatch measurement data showed a mean daily sleep duration of participants to be 437.5 ± 43.1 (372.5 – 509.4) minutes. Mean sleep efficiency (minutes of sleep divided by minutes of time in bed) and mean number of awakenings were 87.4±4.3 (75.4-93.4) minutes and 32.1±6.4 (22.3-42.7) awakenings, respectively. The median time for wake after sleep onset (WASO) was 34.5±10.5 (18.3-67.4) minutes. The mean bone mineral density (BMD) for the hips was 1.06±0.14 (0.81-1.28) g/cm2 with a mean BMD of the lumbar spine being 1.24±0.12 (0.92-1.43) g/cm2. Age-matched Z-scores of the hips was 0.31±0.96 (-1.6-2.1) and lumbar spine was 0.53 (IQR: 0.13, 0.98; -2.25-1.55). Neither sleep duration nor sleep efficiency was significantly correlated to BMD of either locations. While WASO was positively associated with hip and spine BMD, this value was not statistically significant in this population. Overall, associations between sleep and BMD of the femur and spine were not seen in this cohort. Further work utilizing a larger cohort will allow for control of covariates while looking for potential associations between bone health, sleep duration and efficiency.
My research is focused on the people of Turkana, a human pastoral population inhabiting Northwest Kenya. The people of Turkana are Nilotic people that are native to the Turkana district. There are currently no conclusive studies done on evidence for genetic lactase persistence in Turkana. Therefore, my research will be on the evolution of lactase persistence in the people of Turkana. The goal of this project is to investigate the evolutionary history of two genes with known involvement in lactase persistence, LCT and MCM6, in the Turkana. Variants in these genes have previously been identified to result in the ability to digest lactose post-weaning age. Furthermore, an additional study found that a closely related population to the Turkana, the Massai, showed stronger signals of recent selection for lactase persistence than Europeans in these genes. My goal is to characterize known variants associated with lactase persistence by calculating their allele frequencies in the Turkana and conduct selection scans to determine if LCT/MCM6 show signatures of positive selection. In doing this, we conducted a pilot study consisting of 10 female Turkana individuals and 10 females from four different populations from the 1000 genomes project namely: the Yoruba in Ibadan, Nigeria (YRI); Luhya in Webuye, Kenya; Utah Residents with Northern and Western European Ancestry (CEU); and the Southern Han Chinese. The allele frequency calculation suggested that the CEU (Utah Residents with Northern and Western European Ancestry) population had a higher lactase persistence associated allele frequency than all the other populations analyzed here, including the Turkana population. Our Tajima’s D calculations and analysis suggested that both the Turkana population and the four haplotype map populations shows signatures of positive selection in the same region. The iHS selection scans we conducted to detect signatures of positive selection on all five populations showed that the Southern Han Chinese (CHS), the LWK (Luhya in Webuye, Kenya) and the YRI (Yoruba in Ibadan, Nigeria) populations had stronger signatures of positive selection than the Turkana population. The LWK (Luhya in Webuye, Kenya) and the YRI (Yoruba in Ibadan, Nigeria) populations showed the strongest signatures of positive selection in this region. This project serves as a first step in the investigation of lactase persistence in the Turkana population and its evolution over time.