Sleep in the land of the midnight sun and polar night: The Tromsø study

Sivertsen, Børge; Friborg, Oddgeir; Pallesen, Ståle; Vedaa, Øystein; Hopstock, Laila Arnesdatter

doi:10.1080/07420528.2020.1845191

Cited by 14 publications

(11 citation statements)

References 32 publications

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“…Also, most participants were included during winter, which might negatively affect sleep [ 48 , 49 ] and thus could have resulted in higher prevalence of sleep complaints compared to the general population. However, the observed prevalence of sleep complaints in our study was comparable to those previously reported in the Tromsø Study [ 35 ] and the importance of seasonal differences in sleep is still a matter of debate [ 50 ]. In contrast with previous intervention studies [ 23 , 31 , 32 ], our study did not use the Pittsburgh Sleep Quality Index (PSQI) [ 51 ].…”

Section: Discussionsupporting

confidence: 89%

No improvement of sleep from vitamin D supplementation: insights from a randomized controlled trial

et al. 2021

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Background Vitamin D has been linked to sleep health in observational studies. Data from randomized controlled trials (RCTs) with vitamin D is scarce. Methods This study presents the results of a secondary analysis of 189 vitamin D insufficient participants (47.1% women) in a previously performed RCT, of which 92 were randomized to vitamin D (100,000 IU (2500 μg) as a bolus dose followed by 20,000 IU (500 μg) per week), and 97 to placebo. At baseline and after 4 months at the end of the study serum 25-hydroxyvitamin D (s-25(OH)D) was measured, and the study questionnaire assessing sleep duration, daytime sleepiness, and symptoms of insomnia, was completed. Results At baseline, mean s-25(OH)D was 35.0 ± 11.8 and 35.5 ± 13.3 nmol/L in the vitamin D and placebo groups, respectively. After four months, we found no statistically significant differences between the intervention groups in any of the assessed sleep outcomes, neither when stratified by sex, nor when performed in subgroups based on baseline or end of study s-25(OH)D level or presence of sleep complaints at baseline. Conclusions We were not able to demonstrate a significant effect of vitamin D supplementation on sleep in this vitamin D insufficient population.

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Section: Discussionsupporting

confidence: 89%

No improvement of sleep from vitamin D supplementation: insights from a randomized controlled trial

et al. 2021

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“…Insomnia posed similar risk of BSI with seasonal variations in light exposure in our study. This could be explained by insomnia being a stable trait, not being affected by seasonal variation neither at 63°–65° degrees north where the HUNT study is performed nor further north near the polar circle (Shochat et al, 2019; Sivertsen, Friborg, Pallesen, Vedaa, & Hopstock, 2020). When analyzing risk of BSI in the population not using sedatives, risk was 50% among participants having all three cumulative insomnia symptoms, which is a higher than the 40% risk with three cumulative insomnia symptoms in the total population.…”

Section: Discussionmentioning

confidence: 99%

Insomnia symptoms and risk of bloodstream infections: prospective data from the prospective population-based HUNT Study, Norway

Thorkildsen¹,

Laugsand

Nilsen

et al. 2022

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Objective: Previous research suggest decreased immune function and increased risk of infections in persons with insomnia. We examined the effect of insomnia symptoms on risk of bloodstream infections (BSI) and BSI–related mortality in a population–based prospective study. Methods: A total of 53,536 participants in the Norwegian HUNT2 study (1995–97) were linked to prospective data on clinically relevant BSIs until 2011. In Cox regression, we estimated hazard ratios (HRs) with 95% confidence interval (CI) for a first–time BSI and for BSI related mortality (BSI registered ≤30 days prior to death) associated with insomnia symptoms. Results: Compared with participants who reported ″no symptoms of insomnia ″, participants reporting having ″difficulty initiating sleep ″ often/almost every night had a HR for a first-time BSI of 1.14 (95% CI 0.96–1.34). Participants reporting ″difficulties maintaining sleep ″ often/almost every night had a HR of 1.19 (95% CI 1.01–1.40), whereas those having a ″feeling of non–restorative sleep ″ once a week or more had a HR of 1.23 (95% CI 1.04–1.46). Participants experiencing all three above insomnia symptoms frequently had a HR of 1.39 (1.04–1.87) and being troubled by insomnia to a degree that affected work performance was associated with a HR of 1.41 (95% CI 1.08–1.84). The HRs for BSI related mortality suggest an increased risk with increasing insomnia symptoms, but confidence intervals are wide and inconclusive. Conclusions: We found that frequent insomnia symptoms and insomnia symptoms that affected work performance was associated with a weak positive increased risk of BSI.

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“…Indeed, studies from high latitudes have found some sleep phase delay, with a slight increase in insomnia problems and fatigue during the winter as compared to the summer season ( Husby and Lingjaerde, 1990 ; Johnsen et al, 2012 , 2013 ; Friborg et al, 2014 ). However, results from a recent population-based study in Northern Norway found little evidence of seasonal variations in sleep ( Sivertsen et al, 2020 ), even though the amount of daylight varied from 0 to 24 h across the year.…”

Section: Discussionmentioning

confidence: 99%

The Epidemiology of Insomnia and Sleep Duration Across Mental and Physical Health: The SHoT Study

et al. 2021

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ObjectiveNumerous epidemiological studies have been conducted to examine the prevalence and comorbidities of insomnia and document sleep duration, but a common limitation in many studies is the lack of use of agreed-upon definitions of insomnia, as well as insufficient statistical power to examine comorbid mental and physical disorders/conditions.AimTo examine the prevalence of insomnia operationalized according to formal DSM-5 criteria and differences in mean sleep duration across a wide range of mental and physical disorders, examining men and women separately.Materials and MethodsData stem from the SHoT study (Students’ Health and Wellbeing Study), a national survey of all college and university students in Norway. In all, 162,512 students aged 18–35 received an invitation to participate, of whom 50,054 students completed the internet-based survey (attendance rate: 30.8%). Insomnia was defined according to the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) criteria and sleep duration was calculated separately for weekdays and weekends. Self-reported mental and physical disorders/conditions were assessed using a pre-defined list modified to fit this age group. Pearson chi-squared tests were used to examine the prevalence of insomnia across the various mental and physical disorders/conditions in men and women separately, and log-link binomial regression analysis were used to calculate effect-sizes, adjusting for age.ResultsThe prevalence of insomnia in both sexes was significantly higher across all mental disorders compared with a healthy reference group. Among females, the prevalence of insomnia ranged from 61.3% for comorbid depression (adj. RR = 2.49, 95% CI: 2.40) to 83.3% for comorbid schizophrenia (adj. RR = 3.37, 95% CI: 2.61–4.35). For males, the insomnia prevalence ranged from 32.3% for comorbid autism/Asperger (adj. RR = 2.02, 95% CI: 1.39–2.92) to 74.2% for comorbid eating disorder (adj. RR = 4.51, 95% CI: 3.87–5.27). The overall prevalence of insomnia was also significantly higher across most physical conditions compared with the healthy reference group, although generally lower compared to the mental disorders. For females, the insomnia prevalence ranged from 25% for comorbid multiple sclerosis (not significant) to 65.4% for comorbid chronic fatigue syndrome/ME (adj. RR = 2.66, 95% CI: 2.44–2.89). For males, the insomnia prevalence ranged from 20% for both comorbid cancer and diabetes (not significant) to 74.2% for comorbid fibromyalgia (adj. RR = 4.35, 95% CI: 2.96–6.39). Similar patterns were observed for sleep duration, with a significantly shorter sleep duration for across many physical disorders, but especially mental disorders.ConclusionInsomnia and short sleep duration are strongly associated with a range of different disorders and conditions. Insomnia is most strongly associated with mental disorders, and physical conditions characterized by some level of psychological or psychosomatic properties.

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Sleep in the land of the midnight sun and polar night: The Tromsø study

Cited by 14 publications

References 32 publications

No improvement of sleep from vitamin D supplementation: insights from a randomized controlled trial

No improvement of sleep from vitamin D supplementation: insights from a randomized controlled trial

Insomnia symptoms and risk of bloodstream infections: prospective data from the prospective population-based HUNT Study, Norway

The Epidemiology of Insomnia and Sleep Duration Across Mental and Physical Health: The SHoT Study

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