Evening-types show highest increase of sleep and mental health problems during the COVID-19 pandemic - Multinational study on 19,267 adults

Study Objectives

Individual circadian type is a ubiquitous trait defining sleep, with eveningness often associated with poorer sleep and mental health than morningness. However, it is unknown whether COVID-19 pandemic has differentially affected sleep and mental health depending on the circadian type. Here, the differences in sleep and mental health between circadian types are examined globally before and during the COVID-19 pandemic.

Methods

The sample collected between May and August 2020 across 12 countries/regions consisted of 19 267 adults with information on their circadian type. Statistical analyses were performed by using Complex Sample procedures, stratified by country and weighted by the number of inhabitants in the country/area of interest and by the relative number of responders in that country/area.

Results

Evening-types had poorer mental health, well-being, and quality of life or health than other circadian types during the pandemic. Sleep–wake schedules were delayed especially on working days, and evening-types reported an increase in sleep duration. Sleep problems increased in all circadian types, but especially among evening-types, moderated by financial suffering and confinement. Intermediate-types were less vulnerable to sleep changes, although morningness protected from most sleep problems. These findings were confirmed after adjusting for age, sex, duration of the confinement, or socio-economic status during the pandemic.

Conclusions

These findings indicate an alarming increase in sleep and mental health problems, especially among evening-types as compared to other circadian types during the pandemic.

Comparative study of colony hybridization with synthetic oligonucleotide probes and enzyme-linked immunosorbent assay for identification of enterotoxigenic Escherichia coli

On the basis of the published nucleotide sequences of the genes that code for the heat-labile toxin LTh and the heat-stable toxins STaI and STaII of human enterotoxigenic Escherichia coli, a 34-mer and two 33-mer oligonucleotide probes were synthesized. To compare their relative efficacies in the detection and differentiation of enterotoxigenic E. coli, a colony hybridization technique using these probes and a GM1 ganglioside enzyme-linked immunosorbent assay using monoclonal anti-LT and anti-ST antibodies were used with 76 strains of E. coli with known enterotoxin profiles. For further evaluation of probe specificity, the enterotoxigenic bacteria Vibrio cholerae O1 and non-O1 and Yersinia enterocolitica were examined with the colony hybridization technique. The sensitivity of colony hybridization compared favorably with that of GM1 ganglioside enzyme-linked immunosorbent assay, and the two assays showed a high level of concordance in specific detection and differentiation of E. coli with various enterotoxin profiles (kappa = 0.906, P less than 0.00001). The probes did not hybridize with DNAs from strains of V. cholerae O1 or non-O1 or Y. enterocolitica.

Case fatality of meningococcal disease in western Norway

In the period 1976-84, 211 patients hospitalized with meningococcal disease were examined for possible relation between various epidemiological parameters and fatality. The peak incidences were in the age groups 0-4 and 13-18 years, with teenage girls peaking 2 years ahead of the boys. The overall case fatality rate was 8.5%. In septicemic patients (without meningitis) hypotension and/or ecchymoses on admission correlated strongly with a poor prognosis. Most deaths occurred during the months of March and November, and none during the summer months. There was a significant clustering of deaths among patients admitted during the morning hours, probably due to delayed diagnosis and treatment during the night. Since almost all patients who died had skin bleedings on admission, frequent examination of the skin in cases with acute unexplained fever might have saved lives.

The Short-Term Efficacy of an Unguided Internet-Based Cognitive-Behavioral Therapy for Insomnia: A Randomized Controlled Trial With a Six-Month Nonrandomized Follow-Up

OBJECTIVE

Insomnia is a major health problem, and the need for effective and accessible treatment is urgent. The aim of the current study was to evaluate the short-term efficacy of an unguided Internet-based cognitive-behavioral treatment program for insomnia (CBTi), called SHUTi (Sleep Healthy Using the Internet).

METHODS

This study used a parallel arm randomized controlled trial in Norway. Participants were randomly allocated to the SHUTi condition or a Web-based patient education condition. Both groups were assessed before and after the nine-week intervention period (online sleep diaries and questionnaires). The SHUTi participants were reassessed in a six-month nonrandomized follow-up. Primary outcome measures were the Insomnia Severity Index (ISI) and the Bergen Insomnia Scale (BIS).

RESULTS

A total of 181 participants were included in the study; SHUTi condition (n = 95), patient education condition (n = 86). Intention-to-treat mixed-model repeated-measures analysis revealed that the SHUTi group had better short-term outcomes compared with the patient education group on most sleep measures. The SHUTi group showed a significant decrease on the primary outcomes, the ISI (d_between = -1.77, 95% CI = -2.23, -1.31) and the BIS (d_between = -1.00, 95% CI = -1.32, -.68). Improvements were maintained among the completing SHUTi participants at the six-month nonrandomized follow-up. However, dropout attrition was high.

CONCLUSION

Unguided Internet-based CBTi produced significant short-term improvements in sleep in patients with chronic insomnia. This highlights the benefits of making Internet-delivered CBTi programs available as a standard first-line treatment option in public health services. Nevertheless, the rate of dropout attrition (participants not completing post-assessment) in this trial limits the generalizability of the findings.

Sleep and circadian problems during the coronavirus disease 2019 (COVID-19) pandemic: the International COVID-19 Sleep Study (ICOSS)

This protocol paper describes the development of an international collaboration to survey several thousand adults from different countries around the world about their sleep during the coronavirus disease 2019 (COVID-19) pandemic. It is based on the development of a harmonised survey with 50 questions (106 different items) on sleep habits and sleep symptoms that permit comparability of information. The harmonised questionnaire may be used in anonymous cross-sectional surveys, and the instruments within the questionnaire may also be used in prospective studies and clinical studies. The aim was to develop a questionnaire to sample a variety of sleep-wake disorders and other symptoms likely to be caused by prolonged social confinement or by having had COVID-19. The questionnaire was designed to be: (a) simple and, (b) free to use, for research purposes, (c) multilingual, and (d) comprehensive. It can be completed in <30 min. By the end of June 2020, the survey questionnaire had been administered in Austria, Canada, China, Finland, France, Germany, Hong Kong, Italy, Japan, Norway, Poland, Sweden, UK and USA. Research questions to be addressed by the pooled data derived from the participating sites focus on describing the nature and rates of various sleep and circadian rhythms symptoms, as well as their psychological and medical correlates, that arise at various points during the COVID-19 pandemic.

Working Conditions and Individual Differences Are Weakly Associated with Workaholism: A 2-3-Year Prospective Study of Shift-Working Nurses

This study focuses on individual differences and the demand-support-control model in relation to workaholism. We hypothesized that unfavorable working conditions (high job demands, low job control/decision latitude, and low social support at work) and individual differences concerning sleep/wake-related variables (high flexibility, high morningness, and low languidity) would be related to workaholism measured 2–3 years later. Survey data stemmed from a prospective cohort of shift-working nurses (N = 1,308). The results showed that social support at work was negatively related to workaholism, whereas job demands were positively related to workaholism. Flexibility in terms of time for working/sleeping was also positively related to workaholism. The analyses further revealed that workaholism was inversely associated with age as well as having a child or having a child move in. Conjointly, the independent variables explained 6.4% of the variance in workaholism, while their relative importance was small overall. After controlling for all other independent variables, high job demands had the strongest relationship (small-to-medium) with workaholism. This implies that less pressure from the external environment to work excessively hard may prevent an increase in workaholic behaviors. Overall, the study adds to our understanding of the relationships between working conditions, individual differences, and workaholism.

Light therapy for behavioural and psychological symptoms of dementia

OBJECTIVES

To review literature concerning the efficacy, clinical practicability and safety of light treatment for behavioural and psychological symptoms of dementia (BPSD).

METHOD

Data collection included computer literature searches (MEDLINE, PsycINFO and Cochrane) and checks of references, covering the period of January 1980-September 2003. Trials were searched for evidence for treatment efficacy and for their consideration of the treatment's clinical practicability and evidence of adverse effects.

RESULTS

Results from randomised controlled trials (RCT) indicated some evidence of improvement in aspects of sleep disturbances and circadian activity rhythmicity. One RCT study indicated better response in patients with vascular dementia compared to Alzheimer's disease. By and large, non-RCT studies reported improvement in BPSD including sleep disturbances, agitation and activity rhythm disturbances. Few studies commented on the treatment's practicability and safety.

CONCLUSION

Although there is some evidence for influence of light therapy on sleep and circadian activity rhythmicity, it is not possible to draw any conclusion about efficacy of light therapy for BPSD, or about practicability in clinical settings and safety. There are still too few well designed studies. Suggestions for further research are presented.

Changes in sleep and wakefulness following 5-HT1A ligands given systemically and locally in different brain regions

Serotonin (5-HT) has been implicated in the regulation of vigilance, but whether 5-HT is important for sleep or waking processes remains controversial. This review addresses the role of 5-HT1A receptors in sleep and wakefulness. Systemic administration of 5-HT1A agonists consistently increases wakefulness, whereas slow wave sleep (SWS) and REM (rapid-eye movement) sleep are reduced. However, systemic 5-HT1A agonists also produce a delayed increase in deep slow wave sleep, or an increase in slow wave activity. Intrathecal administration of a selective 5-HT1A agonist produces an increase in SWS, whereas wakefulness is reduced, presumably by stimulating 5-HT1A receptors located presynaptically on primary afferents in the spinal cord. Microinjection of serotonin into the region of the cholinergic basalis neurons produces an increase in slow wave activity, presumably by stimulating 5-HT1A receptors. Microdialysis perfusion of a selective 5-HT1A agonist into the dorsal Raphe nucleus causes an increase in REM sleep, whereas the other sleep/wake stages are unaltered. The REM sleep increase is likely due to a decrease in 5-HT neuronal activity, and thereby reduced 5-HT neurotransmission in projection areas, e.g. the laterodorsal and pedunculopontine tegmental nuclei. Direct injection of a selective 5-HT1A agonist into the pedunculopontine tegmental nuclei reduces REM sleep, consistent with such a hypothesis. These complex sleep/wake data of 5-HT1A ligands suggest that 5-HT1A receptor activation may increase waking, increase slow wave sleep or increase REM sleep depending on where the 5-HT1A receptors are located within the central nervous system.

The 5-HT1A receptor antagonist p-MPPI blocks 5-HT1A autoreceptors and increases dorsal raphe unit activity in awake cats

The effects of the putative 5-HT1A receptor antagonist 4-iodo-N-[2-[4-(methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl-benzam ide (p-MPPI) were examined on the activity of serotonergic dorsal raphe nucleus neurons in freely moving cats. Systemic administration of p-MPPI produced a dose-dependent increase in firing rate. This stimulatory effect of p-MPPI was evident during wakefulness (when serotonergic neurons display a relatively high level of activity), but not during sleep (when serotonergic neurons display little or no spontaneous activity). p-MPPI also blocked the ability of the 5-HT1A receptor agonist 8-hydroxy-(2-di-n-propylamino)tetralin (8-OH-DPAT) to inhibit serotonergic neuronal activity. This antagonism was evident both as a reversal of the neuronal inhibition produced by prior injection of 8-OH-DPAT and as a shift in the potency of 8-OH-DPAT following p-MPPI pretreatment. Overall, these results in behaving animals indicate that p-MPPI acts as an effective 5-HT1A autoreceptor antagonist. The increase in firing rate produced by p-MPPI supports the hypothesis that autoreceptor-mediated feedback inhibition operates under physiological conditions.

Clinically significant discrepancies between sleep problems assessed by standard clinical tools and actigraphy

Background

Sleep disturbances are widespread among nursing home (NH) patients and associated with numerous negative consequences. Identifying and treating them should therefore be of high clinical priority. No prior studies have investigated the degree to which sleep disturbances as detected by actigraphy and by the sleep-related items in the Cornell Scale for Depression in Dementia (CSDD) and the Neuropsychiatric Inventory – Nursing Home version (NPI-NH) provide comparable results. Such knowledge is highly needed, since both questionnaires are used in clinical settings and studies use the NPI-NH sleep item to measure sleep disturbances. For this reason, insight into their relative (dis)advantages is valuable.

Method

Cross-sectional study of 83 NH patients. Sleep was objectively measured with actigraphy for 7 days, and rated by NH staff with the sleep items in the CSDD and the NPI-NH, and results were compared. McNemar's tests were conducted to investigate whether there were significant differences between the pairs of relevant measures. Cohen's Kappa tests were used to investigate the degree of agreement between the pairs of relevant actigraphy, NPI-NH and CSDD measures. Sensitivity and specificity analyses were conducted for each of the pairs, and receiver operating characteristics (ROC) curves were designed as a plot of the true positive rate against the false positive rate for the diagnostic test.

Results

Proxy-raters reported sleep disturbances in 20.5% of patients assessed with NPI-NH and 18.1% (difficulty falling asleep), 43.4% (multiple awakenings) and 3.6% (early morning awakenings) of patients had sleep disturbances assessed with CSDD. Our results showed significant differences (p<0.001) between actigraphy measures and proxy-rated sleep by the NPI-NH and CSDD. Sensitivity and specificity analyses supported these results.

Conclusions

Compared to actigraphy, proxy-raters clearly underreported NH patients' sleep disturbances as assessed by sleep items in NPI-NH and CSDD. The results suggest that the usefulness of proxy-rater measures of sleep may be questionable and further research is needed into their clinical value. The results highlight the need for NH staff to acquire and act on knowledge about sleep and sleep challenges among NH patients.

Trial registration

Registered at www.clinicaltrials.gov (registration number NCT02238652) on July 7th 2014 (6 months after study initiation).

Differentiation of B15 strains of Neisseria meningitidis by DNA restriction endonuclease fingerprinting

The restriction endonuclease fingerprinting technique was applied to meningococcal DNA in an attempt to identify individual strains of Neisseria meningitidis B15 (serogroup B, serotype 15), which causes approximately 90% of cases of meningococcal disease in northern Norway. Thirty representative strains (10 each from asymptomatic pharyngeal carriers, patients with septicemia, and patients with meningitis) were investigated with the restriction endonucleases Hind III and Eco RI. The 10 carrier strains showed a remarkable heterogeneity of fingerprints that rendered each strain easily distinguishable from the others. The 10 strains from the blood and the 10 from the cerebrospinal fluid showed similar but not identical restriction patterns. The results obtained with the two endonucleases were in perfect agreement. Our data suggest that a large number of different B15 clones are present in the population of northern Norway, but that only one single clone causes invasive meningococcal disease.

Sleep duration during the 24-hour day is associated with the severity of dementia in nursing home patients

STUDY OBJECTIVES

To describe the characteristics of 24-h sleep patterns in nursing home patients with dementia, and to determine whether various degrees of dementia have any influence on total sleep duration.

DESIGN AND SETTING

Cross-sectional study in a nursing home population (n = 23) consisting of patients with varying degree of dementia. Sleep was measured with actigraphy for a consecutive period of 14 days, based on individual bed and rising time, which was registered by nursing home staff.

MEASUREMENTS AND RESULTS

Mean age +/- standard deviation was 86.1 +/- 7.0 (range 72-96) and mean Mini-Mental Status Examination Score (MMSE) was 13.4 +/- 5.3 (range 1-21). Ten patients had MMSE < or = 12. Sleep was extremely fragmented, with frequent wake bouts during nighttime and frequent naps during daytime. During the 24-h period, patients spent nearly 13 h asleep, distributed as more than 9 h of nighttime sleep and more than 3 h of daytime sleep. Patients with severe degree of dementia (MMSE < or = 12) slept significantly longer during the 24-h day than patients with lesser degree of dementia (MMSE > 12). There was no significant difference in age between the dementia sub-groups.

CONCLUSION

Sleep duration during the 24-h day was positively correlated with the severity of dementia in nursing home patients. This is in contrast with total sleep time seen in healthy elderly, which shows a gradually decline with age. Changes in sleep patterns in dementia could be explained by co-morbid and environmental factors, as well as unknown pathological changes related to dementing illnesses.

Antibodies against BCG antigen 60 in mycobacterial infection

A sensitive specific radioimmunoassay was developed to measure antibodies against BCG antigen 60, a prominent antigenic component of BCG bacilli which cross-reacts with similar components in many mycobacterial species including Mycobacterium leprae and M tuberculosis. A lepromatous serum pool had anti-BCG-60 activity with a titre of 10(5) and the tuberculoid pool a titre of 10(4). Testing of individual sera showed striking variations within groups of patients with lepromatous and tuberculoid leprosy. In five of the 20 tuberculoid leprosy sera the anti-BCG-60 activity was above the median for the lepromatous group. The current view that antibody formation against mycobacterial antigens is very low in tuberculoid leprosy thus no longer appears to be tenable. Sera from eight patients with active pulmonary tuberculosis also showed a striking variation in anti-BCG-60 content, and the median value of this group was even higher than in those with lepromatous leprosy.

The association between high risk of sleep apnea, comorbidities, and risk of COVID-19: a population-based international harmonized study

PURPOSE

Obstructive sleep apnea (OSA) may increase the risk of severe COVID-19; however, the level of potential modulation has not yet been established. The objective of the study was to determine the association between high risk of OSA, comorbidities, and increased risk for COVID-19, hospitalization, and intensive care unit (ICU) treatment.

METHODS

We conducted a cross-sectional population-based web survey in adults in 14 countries/regions. The survey included sociodemographic variables and comorbidities. Participants were asked questions about COVID-19, hospitalization, and ICU treatment. Standardized questionnaire (STOP questionnaire for high risk of OSA) was included. Multivariable logistic regression was conducted adjusting for various factors.

RESULTS

Out of 26,539 respondents, 20,598 (35.4% male) completed the survey. Mean age and BMI of participants were 41.5 ± 16.0 years and 24.0 ± 5.0 kg/m², respectively. The prevalence of physician-diagnosed OSA was 4.1% and high risk of OSA was 9.5%. We found that high risk of OSA (adjusted odds ratio (aOR) 1.72, 95% confidence interval (CI): 1.20, 2.47) and diabetes (aOR 2.07, 95% CI: 1.23, 3.48) were associated with reporting of a COVID-19 diagnosis. High risk for OSA (aOR 2.11, 95% CI: 1.10-4.01), being male (aOR: 2.82, 95% CI: 1.55-5.12), having diabetes (aOR: 3.93, 95% CI: 1.70-9.12), and having depression (aOR: 2.33, 95% CI: 1.15-4.77) were associated with increased risk of hospitalization or ICU treatment.

CONCLUSIONS

Participants at high risk of OSA had increased odds of having COVID-19 and were two times more likely to be hospitalized or treated in ICU.

Subjective and objective sleepiness among oil rig workers during three different shift schedules

OBJECTIVES

Examine sleepiness in three different shift work schedules (within-subject design) in the offshore oil industry.

METHODS

Sleepiness was measured in 19 oil rig workers, using subjective (Karolinska Sleepiness Scale; Accumulated Time with Sleepiness) and objective measures (reaction time). The work schedule consisted of two weeks of 12 h day work (day shifts), two weeks of 12 h night work (night shifts), and two weeks of swing shift work (one week of night work followed by one week of day work).

RESULTS

Sleepiness was highest during the first days of night and swing shifts, and also in the middle of the swing shift work period, but gradually decreased as the days on the night shift progressed. While at home following the two-week work period, the workers reported more subjective sleepiness after night shift than after day or swing shifts. Reaction time tests during the work period showed no significant differences between the shift schedules. There was a significant shorter reaction time the last day compared to the beginning or middle of the work period.

CONCLUSIONS

Subjective sleepiness was higher during the first days of night work compared to day work, and also when the swing shift workers changed from night work to day work in the middle of the two-week work period. Subjective sleepiness was increased at home following night shifts compared to after day and swing shifts, suggesting that swing shift workers adapted their circadian rhythm during their second period of work, during the day shift week, offshore.

Increased waking as well as increased synchronization following administration of selective 5-HT uptake inhibitors to rats

Sleep and waking stages and EEG power spectra were investigated in rats following saline injections and injection of 10 and 20 mg/kg zimeldine or 10 and 20 mg/kg alaproclate, both selective 5-HT reuptake inhibitors. Following zimeldine there was a biphasic effect on sleep and waking, waking being increased during the first 2 1/2 h of recording, while slow wave sleep (SWS), in particular highly synchronized SWS-2 with high slow wave activity, was increased during the second 2 1/2 h recording period. Analysis of EEG power spectra indicated that the amount of synchronized slow wave activity was also increased within the sleep that occurred during the waking-dominated initial 2 1/2 h period. These data suggest simultaneous appearance of increased waking and increased synchronization following general serotonergic stimulation. They are interpreted as due to effects on different regions of the serotonergic system or on different serotonergic receptors. Consistent with earlier findings, zimeldine also suppressed rapid eye movement (REM) sleep. Following alaproclate, a clear waking effect was present, but only a weak synchronizing effect was seen. This is consistent with data on regional differences in uptake inhibition for zimeldine and alaproclate. Alaproclate also reduced REM sleep. Zimeldine or alaproclate was also administered to rats that had reduced sleep following pretreatment with a moderate dose of parachlorophenylalanine (PCPA). None of the drugs increased waking any further, but the PCPA-pretreated animals that received zimeldine had increased SWS-2, indicating that the SWS-2 increase following zimeldine alone was not a rebound effect.

Insomnia - A Heterogenic Disorder Often Comorbid With Psychological and Somatic Disorders and Diseases: A Narrative Review With Focus on Diagnostic and Treatment Challenges

Patients with insomnia complain of problems with sleep onset or sleep maintenance or early morning awakenings, or a combination of these, despite adequate opportunity and circumstances for sleep. In addition, to fulfill the diagnostic criteria for insomnia the complaints need to be associated with negative daytime consequences. For chronic insomnia, the symptoms are required to be present at least 3 days per week for a duration of at least 3 months. Lastly, for insomnia to be defined as a disorder, the sleep complaints and daytime symptoms should not be better explained by another sleep disorder. This criterion represents a diagnostic challenge, since patients suffering from other sleep disorders often complain of insomnia symptoms. For instance, insomnia symptoms are common in e.g., obstructive sleep apnea and circadian rhythm sleep-wake disorders. It may sometimes be difficult to disentangle whether the patient suffers from insomnia disorder or whether the insomnia symptoms are purely due to another sleep disorder. Furthermore, insomnia disorder may be comorbid with other sleep disorders in some patients, e.g., comorbid insomnia and sleep apnea (COMISA). In addition, insomnia disorder is often comorbid with psychological or somatic disorders and diseases. Thus, a thorough assessment is necessary for correct diagnostics. For chronic insomnia disorder, treatment-of-choice is cognitive behavioral therapy, and such treatment is also effective when the insomnia disorder appears comorbid with other diagnoses. Furthermore, studies suggest that insomnia is a heterogenic disorder with many different phenotypes or subtypes. Different insomnia subtypes may respond differently to treatment, but more research on this issue is warranted. Also, the role of comorbidity on treatment outcome is understudied. This review is part of a Research Topic on insomnia launched by Frontiers and focuses on diagnostic and treatment challenges of the disorder. The review aims to stimulate to more research into the bidirectional associations and interactions between insomnia disorder and other sleep, psychological, and somatic disorders/diseases.

Isolates of Neisseria meningitidis from different sites in the same patient: phenotypic and genomic studies, with special reference to adherence, piliation, and DNA restriction endonuclease pattern

Neisseria meningitidis was isolated from the throat, blood, and cerebrospinal fluid of six patients and from the throat and blood of two patients. All 22 isolates were of serogroup B, serotype 15, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis type IV. Isolates from a single patient always possessed identical DNA restriction endonuclease patterns; this observation strongly suggested genomic identity. In spite of this apparent genomic identity, however, significant differences in piliation and adherence were observed among isolates from different sites in the same patient. Isolates from the throat were significantly more piliated (P less than .001) and adhered to human buccal epithelial cells in vitro in significantly higher numbers (P less than .001) than did isolates from the blood and the cerebrospinal fluid of the same patient. These results indicate that phase shift occurs in N. meningitidis in vivo.

Migraine, tension-type headache and medication-overuse headache in a large population of shift working nurses: a cross-sectional study in Norway

OBJECTIVES

To investigate associations between different types of headaches and shift work.

DESIGN, PARTICIPANTS AND OUTCOME MEASURES

Nurses with different work schedules (day work, two-shift rotation, night work, three-shift rotation) participated in a cohort study with annual surveys that started in 2008/2009. In 2014 (wave 6), a comprehensive headache instrument was included in the survey, in which 1585 nurses participated. Headaches were assessed according to the International Classification of Headache Disorders IIIb. Frequent headache (≥1 day per month), migraine, tension-type headache, chronic headache (headache >14 days per month) and medication-overuse headache (chronic headache + acute headache medication ≥10 days last month) comprised the dependent variables. Adjusted (for sex, age, percentage of full-time equivalent, marital status, children living at home) logistic regression analyses were conducted with work schedule, number of night shifts worked last year, number of quick returns (<11 hours in-between shifts) last year, shift work disorder and insomnia disorder as predictors.

RESULTS

Frequent headache, migraine and chronic headache were associated with shift work disorder (OR 2.04, 95% CI 1.62 to 2.59; 1.60, 1.21 to 2.12; 2.45, 1.25 to 4.80, respectively) and insomnia disorder (OR 1.79, 95% CI 1.43 to 2.23; 1.55, 1.18 to 2.02; 3.03, 1.54 to 5.95, respectively), but not with work schedule, number of night shifts or number of quick returns. Tension-type headache was only associated with >20 night shifts last year (OR 1.41, 95% CI 1.07 to 1.86). Medication-overuse headache was only associated with insomnia disorder (OR 7.62, 95% CI 2.48 to 23.41).

CONCLUSIONS

We did not find any association between different types of headaches and work schedule. However, tension-type headache was associated with high number of night shifts. Nurses with sleep disorders (insomnia disorder and shift work disorder) reported higher prevalence of frequent headaches, migraine, chronic headache and medication-overuse headache (only insomnia) compared with nurses not having insomnia disorder and shift work disorder, respectively.