School of Physiology (ETDs)

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    The effect of two modalities of sleep disruption on immunity in healthy young female participants
    (University of the Witwatersrand, Johannesburg, 2023-07) Ajlan, Zuha; Scheuermaier, Karine; Iacovides, Stella
    Studies have shown that sleep deprivation leads to an inappropriate immune response by elevating pro-inflammatory markers, including interleukin (IL-)1, IL-6, and tumour necrosis factor (TNF-)α. This inappropriate immune activation increases the risk of developing autoimmune disorders. Despite women representing 80% of patients with autoimmune disorders and having a greater prevalence of poor sleep quality and sleep disorders, most experimental human studies investigating sleep and immunity focused on men. Therefore, this study assessed the effect of sleep fragmentation vs sleep restriction on sleep parameters. I then compared the immune response after the two types of sleep disruptions relative to a normal sleep episode and I investigated the association between sleep architecture and immune markers in healthy young women in the follicular phase of their menstrual cycle. Fourteen healthy females underwent a randomised-crossover controlled study consisting of one adaptation night and three randomised, non-consecutive sleep conditions, namely: baseline night (BN, uninterrupted 8 hours of sleep); restriction night (RN, sleep was limited to the first 4 hours of their habitual sleep episode); fragmentation night (FN, eight randomised forced awakenings through an 8-hour sleep opportunity night). Polysomnographic (PSG) sleep recordings were obtained for each condition, and plasma was collected 2.5 hours after their habitual waketime following each condition. A multiplex Luminex assay was used to measure the concentration of nine cytokines. I compared PSG-extracted sleep variables between the three experimental nights. I ran mixed models analyses testing cytokine levels in each sleep condition (RN vs. FN vs. BN) in unadjusted analyses and then adjusting for order of the condition (first vs. second vs. third experimental night), day of follicular phase of the menstrual cycle and age. I also used an unadjusted mixed model analysis to test the association between cytokine levels and each sleep variable. Total sleep time, non-rapid eye movement (NREM) and rapid eye movement (REM) were reduced in FN and RN but were lowest during RN (p<0.001). I found an effect of sleep condition on IL-8 (F = 3.40, P = 0.05) with IL-8 being lower in RN vs FN or BN. There was no effect of condition on the other cytokines in unadjusted or adjusted analyses. Lower wake after sleep onset (WASO) and higher NREM were associated with higher IL-8 concentration regardless of the sleep condition. Lower stage 2 (N2) (F = 6.28, β = -0.001, P = 0.02) and higher stage 3 (N3) (F = 7.01, β = 0.004, P = 0.01) was associated with a higher TNF-α regardless of the sleep condition. In conclusion, the study shows that acute sleep disruption alters sleep architecture and leads to an inappropriate immune activity in young healthy women. Future studies should try and investigate chronic sleep fragmentation vs chronic sleep restriction on the immune system.
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    The Epidemiology of Menstrual Pain in a South African University Population
    (University of the Witwatersrand, Johannesburg, 2023) Futi, Benedicte Malonda; Iacovides, Stella; Scheuermaier, Karine
    Dysmenorrhoea, pain associated with menstruation, is a significant public health concern among young women of reproductive age. Identifying associated risk factors for the development of dysmenorrhoea is essential to minimize the impact of monthly menstrual pain on the daily functioning of these women, both in a personal and professional capacity. However, epidemiological data on the prevalence and associated risk factors for dysmenorrhoea in South Africa are scarce. This study aimed to determine the prevalence of dysmenorrhoea and its associated risk factors in a South African university student and staff population. An online survey was distributed to all 26 public universities across South Africa. The final sample comprised data from 7280 participants, and I found a high prevalence [76.7% (95% CI, 75.7-77.6)] of moderate-to-severe dysmenorrhoea among the respondents. Factors significantly associated with increase odds of experiencing moderate to severe dysmenorrhoea included: having heavy (adjusted OR = 2.749, 95% CI 2.208-3.421; p < 0.001) menstrual flow, having a positive family history of dysmenorrhoea (adjusted OR = 1.615, 95% CI 1.346-1.938; p < 0.001), always experiencing poorer subjective sleep quality [“often” (OR= 1.595, 95% CI 1.16-2.191; p=0.004), “sometimes” (OR= 1.523, 95% CI 1.22-1.902; p=0.0002) and “rarely” (OR=2.046, 95% CI 1.596-2.623; p<0.0001)], and scoring higher on the central sensitisation inventory total score (adjusted OR= 1.033, 95% CI 1.026-1.04; p < 0.001). On the other hand, factors significantly associated with decrease odds of experiencing moderate to severe dysmenorrhoea included: older age at the time of the study (adjusted OR= 0.982, 95% CI 0.967-0.998; p= 0.0285), older age at menarche (adjusted OR = 0.938, 95% CI 0.89-0.989; p= 0.0186), having been pregnant (adjusted OR = 0.757, 95% CI 0.605-0.946; p= 0.0145), lower BMI (adjusted OR = 0.986, 95% CI 0.972-1; p = 0.044), being of European ancestry (adjusted OR = 0.698, 95% CI 0.567-0.859; p = 0.007), and having light menstrual flow (adjusted OR= 0.473, 95% CI 0.373-0.6; p < 0.001). I also found a significant impact of dysmenorrhoea on daily life, with 51.6% of respondents reporting absenteeism from school or work during menses and 88.4% of the respondents requiring pharmacological treatments, such as contraceptive pills and nonsteroidal anti-inflammatory drugs (NSAIDs), to manage their menstrual pain. The study highlights the need for increased awareness, education, and effective interventions aimed at reducing the prevalence and impact of dysmenorrhoea on women's lives. The implications of both the increased central sensitisation (CS) and the sleep-pain reciprocal relationship suggest that they could potentially lead to the development of chronic pain conditions. Future research should further explore the interventions and management strategies that could improve sleep quality and prevent the onset of central sensitisation, thus reducing the risk of developing chronic pain conditions. The findings have important implications for the management of dysmenorrhoea that can improve women's quality of life and promote better health outcomes. These findings also point towards the need to educate women about the importance of seeking medical attention for dysmenorrhoea and the potential long-term implications of untreated dysmenorrhoea