Night shift work and osteoporosis among female blue-collar workers in Poland - a pilot study

Association of caffeine intake and sleep duration with bone mineral density: a cross-sectional study from National Health and Nutrition Examination Survey between 2011 and 2018

OBJECTIVE

The association between sleep duration, caffeine intake, and bone mineral density (BMD) is not well understood, with previous studies providing controversial results. This study explores the associations among caffeine intake, sleep duration, and BMD.

METHODS

Data were sourced from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2018, including 13,457 participants who self-reported sleep duration and caffeine intake, with BMD measured via dual X-ray absorptiometry. Multivariable linear regression models, adjusted for confounders, were used alongside restricted cubic splines to examine dose-response association.

RESULTS

Of all participants, 6821 (50.7%) were males and 6636 were females (49.3%). The mean caffeine intake and sleep duration were 93.4 mg/day and 7.19 h, respectively. RCS results showed that BMD increased with the increase in caffeine intake, especially in the low dose range of 0-200 mg/day. The dose-response association between sleep duration and BMD showed that sleep durations of 0-6 h may promote the increase of BMD, but after sleep durations greater than 6 h, BMD decreases. After adjustment for potential confounders, compared to the lowest referent quartile, individuals with caffeine intake in quartiles 2, 3, and 4 had a positive correlation with BMD (0.62 95% CI: 0.24-1.37; 0.51 95% CI: 0.22-1.13; 0.75 95% CI: 0.41-1.46; P for trend < 0.05). In covariate-adjusted linear regression models, compared with those sleeping 6 h or less per night, the difference in BMD among those sleeping 6-7 h, 7-8 h, and 8-14.5 h per night were 1.81 (95% CI: 0.4122.71), 1.25 (95% CI: 0.55-2.93), and 0.87 (95% CI: 0.38-1.69). Associations of caffeine intake, sleep duration, and BMD stratified by sex and age failed to reach statistical significance.

CONCLUSIONS

Association might exist between the consumption of caffeine, sleep duration, and BMD; however, when stratified by sex and age, the association did not reach statistical significance.

The relationship between night shift-work and thyroid nodule: A field study among the employees of Yazd Electricity Company

BACKGROUND

Night work includes working between 10 pm and 6 am, which has known effects on people's health. One of the hormones influenced by the circadian rhythm is thyroid stimulating hormone (TSH).

OBJECTIVE

Considering the effects of night shift-work on the thyroid gland, the purpose of this study was to investigate the relationship between thyroid nodules and night shift-work among the employees of Yazd Electricity Company.

METHODS

This was a cross-sectional study on employees of Yazd Electricity Company. Demographic information including age, gender, level of education, smoking, work experience and shift- work was recorded and blood pressure, height and weight of the subjects were measured. Thyroid sonography was performed for the subjects. The frequency of thyroid nodules in each group of night shift and non-night shift work groups was determined and compared.

RESULTS

Among 433 participants, 47 people (10.9%) were night shift-workers and 386 people (89.1%) were non-night shift-workers. The frequency of thyroid nodule was 12.8% among night shift-workers and 18.1% among non-night shift-workers, and no significant correlation was seen between two groups (P = 0.438). Also, the frequency of thyroid nodule was not significantly different between two groups in terms of smoking, gender and work experience. Uni-variate and multi-variate logistic regression model showed that old age and high BMI increased the probability of abnormal thyroid sonographic findings by 6% and 8%, respectively.

CONCLUSIONS

There was no relationship between night shift-work and the frequency of thyroid nodule.

The association between night shift work and osteoporosis risk in adults: A cross-sectional analysis using NHANES

Purpose

Through this study, we assess whether night shift work increases the risk of osteoporosis, and explore the effects of age, gender, or lifestyle differences.

Methods

This cross-sectional study included the collection of data from a sample of the US adults who participated in the National Health and Nutrition Examination Survey (NHANES) over a 7.3-year period (2007-2008, 2009-2010, 2017-March2020), including 4408 participants (2351[52.8%] men and 2057[47.2%] women), with an age range of 20-80 years. The primary variables, health status, nutrition, harmful lifestyle habits, and bone mineral density (BMD), were segregated, and analyzed according to different work schedules. Linear regression models were conducted to evaluate correlations of night shift work and T-scores. Associations between night shift work and osteoporosis were examined using logistic regression analyses. All regression models were stratified by gender and age ≥50 years. Osteoporosis was defined as BMD at the femoral neck or total spine equal to or less than 2.5 standard deviations below the mean for youthful people of the same gender. All data were obtained using questionnaires and examinations collected in mobile examination center (MEC) from NHANES.

Results

After multivariate adjustment, night shift work was related to statistically significant decreases of the total spine in T-scores of females aged ≥50 years. Furthermore, night shift work of the overall population (OR = 2.31 [95% CI, 1.03-5.18]; P = 0.043) and females aged ≥50 years (OR = 4.6 [95% CI, 1.21-17.54]; P = 0.025) was related to an increased prevalence of osteoporosis.

Conclusion

Night shift work correlates with a higher risk of osteoporosis in the population of the US adults, with the combined effect of age, gender, and harmful lifestyle.

Night shift work and serum markers of bone turnover in male shift workers

Night shift work is related to sleep disorders, disruption of circadian rhythm and low serum levels of vitamin D. It is known that all these conditions can adversely affect bone mass. The rate of bone turnover can be assessed through the measurement of molecules called bone turnover markers, including C-terminal telopeptide fragment of type I collagen (CTX) and procollagen type I N-terminal propeptide (P1NP). In this study, we evaluated the serum levels of CTX, P1NP and 25-Hydroxy Vitamin D in 82 male subjects (42 daytime workers and 40 night shift workers) to assess the possible risk of osteoporosis in male shift workers. Serum levels of CTX and P1NP were found to be higher in night shift workers than in daytime workers. No significant difference was found in vitamin D levels between night shift and daytime workers. The increased CTX and P1NP levels reveal a higher rate of bone turnover in night shift workers and thus a possible increased risk of osteoporosis in this category of workers compared with daytime workers. In view of this, our results highlight the importance of further studies investigating the bone health in male night shift workers.

Sleep Disruption and Bone Health

PURPOSE OF REVIEW

Review recent literature investigating the relationship between bone health and sleep/circadian disruptions (e.g., abnormal sleep duration, night shift work).

RECENT FINDINGS

Short and long sleep are associated with low bone mineral density (BMD). Recent data from observational studies identified an increased risk of fracture in women with short sleep. Studies suggest that age, sex, weight change, and concurrent circadian misalignment may modify the effects of sleep restriction on bone metabolism. Interventional studies demonstrate alterations in bone metabolism and structure in response to circadian disruption that could underlie the increased fracture risk seen with night shift work. The effects of sleep and circadian disruption during adolescence may have lifelong skeletal consequences if they adversely impact bone modeling. Data suggest that short sleep and night shift work negatively impact bone metabolism and health. Rigorous studies of prevalent sleep and circadian disruptions are needed to determine mechanisms and develop prevention strategies to optimize lifelong skeletal health.

Night shift work and osteoporosis - bone turnover markers among female blue-collar workers in Poland

Osteoporosis is an important public health problem worldwide. Although many factors relating to bone structure have been described so far, the current knowledge on the occupational factors that may affect bone tissue metabolism is strongly limited. Literature data suggest that night shift work, via circadian rhythm disruption, may be considered a potential risk factor. To this date, only five epidemiological studies addressing this problem have been conducted worldwide. The outcomes of three studies confirmed such relationship, namely, a higher fracture risk was found among nurses with a long lifetime duration of night shift work in one study; and a lower bone mineral density was associated with occupational activity during night-time in two studies. In adults, the bone undergoes constant remodelling through bone resorption followed by bone formation. The various molecules released into the circulatory system during these processes are called bone turnover markers. We investigated the possible associations between night shift work and selected bone turnover markers: N-terminal propeptide of type I procollagen (P1NP), C-terminal cross-linked telopeptide of type I collagen (CTX), osteocalcin, osteopontin, fibroblast growth factor 23 (FGF-23) and osteoprotegerin, measured in plasma of 189 female blue-collar workers. A significantly higher bone turnover rate was noted among the women working night shifts than among those working only during the day. This may potentially lead to a future development of osteoporosis in this population even if the macroscopic changes in the bone structure are not detectable. Night shift work is a prevailing occupational characteristics nowadays. It has been estimated that about 15-20% of the working population in Europe and the USA perform work under this system. Thus, the problem of osteoporosis can affect a large part of the working-age population.

Sleep disruptions and bone health: what do we know so far?

PURPOSE OF REVIEW

This review briefly summarizes the growing body of literature addressing the skeletal consequences of sleep and circadian disruption.

RECENT FINDINGS

The most recent data in the field suggest that the diurnal variation in bone turnover markers are because of endogenous circadian rhythmicity linked to clock genes in all bone cells; in a small human intervention study, cumulative sleep restriction with concurrent circadian disruption negatively alter bone turnover markers in a way that could explain the lower BMD and increased fracture risk identified in some prior night shift work studies; abnormal sleep duration and obstructive sleep apnea are associated with low BMD and increased fracture risk in some but not all studies.

SUMMARY

Normal physiology and some animal and human intervention studies suggest that sleep and circadian disruptions, such as night shift work, abnormal sleep durations and obstructive sleep apnea are detrimental to skeletal health. However, additional research in this area is needed to determine which sleep/circadian disturbances are most detrimental to skeletal health, the reversibility of such impairments, and underlying mechanisms.