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dc.contributor.advisorGrimnes, Guri
dc.contributor.authorLarsen, Anette Uhlving
dc.date.accessioned2022-05-20T11:13:38Z
dc.date.available2022-05-20T11:13:38Z
dc.date.issued2022-06-10
dc.description.abstractIn this thesis, the relationship between vitamin D and health-related outcomes has been investigated. More than 21,000 individuals participated in the Tromsø Study 2015-16. The participants donated blood samples and filled in questionnaires regarding their health status, including questions about their sleep health. Using these data, the association between vitamin D and sleep duration, daytime sleepiness, and insomnia (sleeplessness) were explored. In women, a positive association was found between vitamin D and sleep duration, while the prevalence of insomnia was lower in women with a normal vitamin D level compared to women with higher vitamin D levels. To further explore this relationship, the effect of vitamin D supplementation on sleep duration, daytime sleepiness, and prevalence of insomnia was explored. A sleep questionnaire was implemented as part of an ongoing intervention study, originally designed to evaluate the effect of vitamin D supplementation for the prevention of cardiovascular disease. In total, 189 participants with low vitamin D levels at baseline filled in the sleep questionnaire. After four months of treatment, there were no differences in sleep duration, daytime sleepiness, or prevalence of insomnia between the group taking vitamin D versus placebo, neither when stratified by sex, nor by vitamin D level or sleep status at baseline. It was further investigated in another intervention study whether vitamin D supplementation without additional calcium could have a positive effect on bone mineral density, as a preventive measure against deteriorated bone health. In this intervention study, originally designed to evaluate vitamin D for the prevention of type 2 diabetes, it was found that vitamin D supplementation alone had a positive effect on bone mineral density in men, and that the effect appeared to vary according to measurement site.en_US
dc.description.abstractI denne doktorgraden har sammenhengen mellom vitamin D og helserelaterte endepunkter blitt undersøkt. I 2015-16 deltok mer enn 21,000 personer i Tromsøundersøkelsen. Deltakerne donerte blodprøver og svarte på spørreskjema om helsetilstanden, inkludert spørsmål om søvnhelsen. I dette materialet ble sammenhengen mellom vitamin D nivå og søvnlengde, trøtthet på dagtid og insomni (også kjent som søvnløshet) undersøkt. Det ble funnet en positiv sammenheng mellom vitamin D nivå og søvnlengde blant kvinner, samt lavere forekomst av insomni blant kvinner med normale vitamin D nivå sammenlignet med kvinner med høyt vitamin D nivå. For å vite mer om denne sammenhengen, var det ønskelig å undersøke effekten av vitamin D tilskudd på søvnlengde, trøtthet på dagtid og forekomst av insomni. Det ble derfor inkludert et spørreskjema om søvnhelsen i en pågående intervensjonsstudie, som opprinnelig undersøkte effekten av vitamin D tilskudd i forebygging av hjerte- og karsykdom. Totalt 189 deltakere med lave vitamin D nivå ved studiestart fylte ut spørreskjemaet. Etter fire måneders behandling var det ingen forskjell i søvnlengde, trøtthet på dagtid eller forekomst av insomni mellom deltakere som hadde fått vitamin D og deltakere som hadde fått placebo (narremedisin). Det var heller ingen forskjeller stratifisert på kjønn, vitamin D nivå- eller søvnproblemer ved studiestart. Videre ble det i en annen intervensjonsstudie undersøkt om vitamin D tilskudd uten tillegg av kalsium kunne ha en positiv virkning på beintettheten, som et forebyggende tiltak mot forringet beinhelse. I denne studien, som opprinnelig undersøkte om vitamin D kunne forebygge utvikling av type 2 diabetes, hadde vitamin D en positiv effekt på beintettheten hos menn, og effekten varierte avhengig av hvor beintettheten ble målt.en_US
dc.description.doctoraltypeph.d.en_US
dc.description.popularabstractBackground: The role of vitamin D in health remains unsettled. The present thesis aimed to examine the role of vitamin D in both skeletal and extra-skeletal outcomes. Methods: Using data from a large population-based study and a 4 months randomized controlled trial (RCT) with vitamin D, the association and causal relationship between vitamin D and self-reported sleep measures were investigated (Paper I-II). Using data from another RCT, the effect of 5 years vitamin D supplementation (without additional calcium) on bone mineral density (BMD) was investigated (Paper III). Results/Conclusions: The findings of the present thesis suggest that the association between vitamin D and self-reported sleep measures (if any) is at best small, and do not support a causal relationship. Further, the present thesis support that vitamin D may have a small positive effect on femoral neck BMD in men, but this finding is controversial according to previous literature.en_US
dc.description.sponsorshipThe present thesis and the included papers have been funded by UiT The Arctic University of Norway. In addition, the following financial sources are credited: The work with Paper I was supported by grants from the North Norway Regional Health Authorities (grant number SFP1277-16). In Paper II, the main study was supported by grants from the North Norway Regional Health Authorities (grant number SFP1277-16) and the publication charges were funded through UiT The Arctic University of Norway's Publishing Agreements. In Paper III, the main study was supported by grants from the Novo Nordisk Foundation (Grant R195-A16126), the North Norway Regional Health Authorities (Grant 6856/SFP1029-12), the Norwegian Diabetes Association, and the Research Council of Norway (Grant 184766).en_US
dc.identifier.urihttps://hdl.handle.net/10037/25239
dc.language.isoengen_US
dc.publisherUiT The Arctic University of Norwayen_US
dc.publisherUiT Norges arktiske universiteten_US
dc.relation.haspart<p>Paper I: Larsen, A.U., Hopstock, L.A., Jorde, R. & Grimnes, G. Vitamin D and sleep in the Tromsø study: Results from a population-based health survey. (Manuscript). <p>Paper II: Larsen, A.U., Hopstock, L.A., Jorde, R. & Grimnes, G. (2021). No improvement of sleep from vitamin D supplementation: insights from a randomized controlled trial. <i>Sleep medicine: X, 3</i>, 100040. Also available in Munin at <a href=https://hdl.handle.net/10037/24333>https://hdl.handle.net/10037/24333</a>. <p>Paper III: Larsen, A.U., Grimnes, G. & Jorde, R. (2017). The effect of high-dose vitamin D3 supplementation on bone mineral density in subjects with prediabetes. <i>Osteoporosis International, 29</i>(1), 171-180. Also available at <a href=https://doi.org/10.1007/s00198-017-4222-x>https://doi.org/10.1007/s00198-017-4222-x</a>. Accepted manuscript version available in Munin at <a href=https://hdl.handle.net/10037/13261>https://hdl.handle.net/10037/13261</a>.en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2022 The Author(s)
dc.subject.courseIDDOKTOR-003
dc.subjectVDP::Medical disciplines: 700::Health sciences: 800::Epidemiology medical and dental statistics: 803en_US
dc.subjectVDP::Medisinske Fag: 700::Helsefag: 800::Epidemiologi medisinsk og odontologisk statistikk: 803en_US
dc.subjectVDP::Medical disciplines: 700::Clinical medical disciplines: 750::Endocrinology: 774en_US
dc.subjectVDP::Medisinske Fag: 700::Klinisk medisinske fag: 750::Endokrinologi: 774en_US
dc.subjectTromsøundersøkelsenen_US
dc.subjectThe Tromsø Studyen_US
dc.titleVitamin D: Relations with Sleep and Bone Mineral Density. Insights from the Tromsø Study and randomized controlled trialsen_US
dc.typeDoctoral thesisen_US
dc.typeDoktorgradsavhandlingen_US


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