Dynamic blood pressure changes and recovery under different work shifts in young women

Chrono-nutrition for hypertension

Despite the advancement in blood pressure (BP) lowering medications, uncontrolled hypertension persists, underscoring a stagnation of effective clinical strategies. Novel and effective lifestyle therapies are needed to prevent and manage hypertension to mitigate future progression to cardiovascular and chronic kidney diseases. Chrono-nutrition, aligning the timing of eating with environmental cues and internal biological clocks, has emerged as a potential strategy to improve BP in high-risk populations. The aim of this review is to provide an overview of the circadian physiology of BP with an emphasis on renal and vascular circadian biology. The potential of Chrono-nutrition as a lifestyle intervention for hypertension is discussed and current evidence for the efficacy of time-restricted eating is presented.

Evaluation of the Diurnal Cycle of Blood Pressure and Sleep in Shift Workers

BACKGROUND

Circadian misalignment of physiological factors in shift workers is poorly studied in the Indian population. In the present study, 24-hour blood pressure measurements were taken on the same subject twice, once during his morning and night shifts. Sleep was also monitored by a self-reported sleep diary, which was confirmed with an activity monitor, and the sleep quality was assessed using sleep questionnaires.

OBJECTIVE

This study aimed to discover the pattern of blood pressure variation, the dipping and non-dipping status, and its correlation with sleep.

METHODOLOGY

This observational study was conducted in the Department of Physiology, All India Institute of Medical Sciences (AIIMS), Rishikesh, from April 2019 to September 2019, among security guards working rotating shifts in the Rishikesh hospital premises. Participants were given an activity sheet with instructions to document their daily activities for a complete 24-hour period on the designated measurement day, including recording the time of waking up and going to sleep. A wrist-worn activity monitor was utilised to assess the self-reported sleep duration provided by each participant on the activity sheet.

RESULTS

The present study showed the mean age of the participants as 27.03 ± 2.71 years, along with a mean body mass index (BMI) of 22.10 ± 1.64. Sleep duration was significantly higher during the morning shift (5.81 ± 1.08 hours) compared to the night shift (4.02 ± 1.70 hours) on the day of ambulatory blood pressure monitoring (ABPM) recording. The mean difference in systolic blood pressure between night shift workers between their awake and sleep periods was 15.91 ± 8.44 mmHg. However, no statistically significant disparity was seen when comparing the systolic blood pressure at the 24-hour mark during wakefulness and sleep between those working morning and night shifts (p >0.05).

CONCLUSION

The current study's findings indicate that participation in shift work, particularly night shift work, could potentially play a role in the emergence of irregular circadian blood pressure patterns and potentially lead to a lack of nocturnal blood pressure decline.

The association between sleep disturbances and blood pressure variability: a review of the literature

STUDY OBJECTIVES

Sleep disturbances are an underrecognized public health issue that results in various adverse outcomes and disturbed quality of life. Blood pressure variability (BPV) is an emerging entity in assessing cardiovascular disease risk and accumulating evidence suggests that BPV is closely associated with end-organ damage. This review aims to explore the association between sleep disturbances and BPV.

METHODS

A comprehensive systematic literature search was conducted electronically using Web of Science, Ovid MEDLINE, , and SCOPUS. The electronic search was restricted to relevant English-language studies published between 1985 and August 2020. Most studies were prospective cohorts in design. After applying eligibility criteria, 29 articles were included for synthesis.

RESULTS

This review shows that sleep disturbances are linked to short-term, midterm, and long-term BPV. Restless legs syndrome, shift work, insomnia, short sleep, long sleep, obstructive sleep apnea, and sleep deprivation were all positively associated with systolic blood pressure or diastolic blood pressure fluctuations.

CONCLUSIONS

Given the prognostic implications of BPV and sleep disturbances on cardiovascular mortality, recognizing and treating both disorders is essential. More research is needed to examine the impact of sleep disorder treatment on BPV and cardiovascular mortality.

CITATION

Al Haddad N, Costanian C, Zibara V, et al. The association between sleep disturbances and blood pressure variability: a review of the literature. J Clin Sleep Med. 2023;19(8):1533-1544.

Shift work and cardiovascular strain on working and non-working days

BACKGROUND

Shift work is often associated with adverse effects on cardiovascular health of employees. Only a few studies address the strain of shift and day workers on non-working days compared to working days.

AIMS

This study aims to determine how the cardiovascular strain of hotel and catering industry (HCI) employees who work alternating shifts differs from those working normal day shifts-on both a working day (WD) and a non-working day (ND).

METHODS

The sample consisted of 60 alternating shift (morning and afternoon, mean age: 31.5 ± 8.5 years) and 88 day workers (mean age: 35.3 ± 9.4 years). A 24-h ambulatory measurement of blood pressure (BP) and heart rate (HR) on WD and ND with the time phases DAY, SLEEP, and 24-h TOTAL was used to analyse cardiovascular strain. BP status was assessed by self-measurement (36% hypertensives).

RESULTS

The total strain over 24 h was slightly higher on WD than ND (mean BP: 134/79 versus 127/75 mmHg, P = 0.002-0.020; mean HR: 78 versus 75 bpm, P = 0.055). In trend, shift workers had higher systolic BP than day workers during the individual time phases of DAY, SLEEP, and 24-h TOTAL on WD. Known cardiovascular risk factors emerged as critical determinants of cardiovascular strain: older age, male gender, and hypertensive blood pressure status.

CONCLUSIONS

The results revealed no clear association between the alternating shift system in HCI and increased cardiovascular strain. The 24-h ambulatory measurement is considered ideal for determining cardiovascular strain in everyday life and under working conditions.

The relationship between rotating shift work and blood pressure among nurses working in hospitals of Abadan, Iran

Hypertension is a major risk factor for developing cardiovascular disease. Various factors such as occupational and environmental risk factors affect blood pressure. Shift work is considered to be an occupational stressor. The aim of this study was to determine the relationship between rotating shift work and blood pressure among nurses working in hospitals associated with faculty of medical science. This cross-sectional and descriptive-analytic study was conducted on nurses who worked in three hospitals associated with faculty of medical science, located in Abadan, southwest of Iran from September until December 2019. The sample size was 120 participants and divided into 60 rotating shift workers and 60 day workers (non-shift workers). The nurses were selected through the stratified random sampling technique. Demographic data, smoking status, and medical and occupational history were collected through a check list and interviews. Blood pressure was measured using a digital sphygmomanometer. Data were analyzed by the Mann-Whitney U, chi-square, Pearson's correlation coefficient and logistic regression by using SPSS software version 22. There was statistically significant difference in blood pressure between day workers and rotating shift workers (p ≤ 0.001). By logistic regression analyses, and even after adjusting for confounding variables, rotating shift work was associated with a higher prevalence of hypertension (OR: 1.76 [95%CI: 1.11-2.80]). The findings of this study showed that rotating shift workers have a higher incidence of hypertension than day workers. Therefore, a particular follow-up of rotating shift workers should be recommended to screen workers for hypertension.

Should public safety shift workers be allowed to nap while on duty?

Fatigue and sleep deficiency among public safety personnel are threats to wellness, public and personal safety, and workforce retention. Napping strategies may reduce work-related fatigue, improve safety and health, yet in some public safety organizations it is discouraged or prohibited. Our aim with this commentary is to define intra-shift napping, summarize arguments for and against it, and to outline potential applications of this important fatigue mitigation strategy supported by evidence. We focus our discussion on emergency medical services (EMS); a key component of the public safety system, which is comprised of police, fire, and EMS. The personnel who work in EMS stand to benefit from intra-shift napping due to frequent use of extended duration shifts, a high prevalence of personnel working multiple jobs, and evidence showing that greater than half of EMS personnel report severe fatigue, poor sleep quality, inadequate inter-shift recovery, and excessive daytime sleepiness. The benefits of intra-shift napping include decreased sleepiness and fatigue, improved recovery between shifts, decreased anxiety, and reduced feelings of burnout. Intra-shift napping also mitigates alterations in clinician blood pressure associated with disturbed sleep and shift work. The negative consequences of napping include negative public perception, acute performance deficits stemming from sleep inertia, and the potential costs associated with reduced performance. While there are valid arguments against intra-shift napping, we believe that the available scientific evidence favors it as a key component of fatigue mitigation and workplace wellness. We further believe that these arguments extend beyond EMS to all sectors of public safety.

Ambulatory blood pressure monitoring among emergency medical services night shift workers

OBJECTIVES

Higher 24-hour blood pressure (BP) and blunted BP dipping during sleep and night-time hours are associated with adverse health outcomes. Night shift work may affect 24-hour BP and dipping patterns, but empirical data in emergency medical services (EMS) clinician shift workers are sparse. We implemented ambulatory blood pressure monitoring (ABPM) in EMS workers to characterise BP during night shift work versus a non-workday, and sleep versus wake.

METHODS

Participants worked night shifts. Hourly ABPM and wrist actigraphy (to measure sleep) were collected during two 24-hour periods, one scheduled night shift and one non-workday. Blunted BP dipping was defined as a BP decrease of <10%.

RESULTS

Of 56 participants, 53 (53.6% female, mean age 26.5 (SD 7.5) years) completed the study. During daytime sleep on a workday, 49.1% of participants had blunted systolic BP (SBP) or diastolic BP (DBP) dipping. During night-time sleep on a non-workday, 25% had blunted SBP dipping and 3.9% blunted DBP dipping. Blunted SBP or DBP dipping occurred among all participants who did not nap during the night shift or who napped <60 min. Blunted SBP dipping occurred in only 14.3% of participants who napped 60-120 min.

CONCLUSIONS

During night shift work, the BP dipping of EMS shift workers is blunted; however, most who nap for 60 min or longer experience a healthy dip in BP. The potential health consequences of these observations in EMS clinicians warrant further study.

The relation of work-related factors with ambulatory blood pressure and nocturnal blood pressure dipping among aging workers

Objectives

Individuals with reduced nocturnal blood pressure (BP) dipping are at increased risk of cardiovascular disease compared to persons with normal BP dipping. Although the relation of work-related factors and BP has been studied extensively, very little is known of the association between work-related factors and 24-h BP patterns in aging workers. We examined the cross-sectional relation of work-related risk factors, including occupational status, work-time mode, job demands and job control, with ambulatory BP in aging workers, focusing on nocturnal BP dipping.

Methods

208 workers (mean age 62 ± 3 years; 75% women) from two Finnish population-based cohort studies underwent 24-h ambulatory BP monitoring. Work-related factors were inquired using a questionnaire. Nocturnal BP dipping was calculated as [1 − (asleep BP/awake BP)] × 100.

Results

Shift workers demonstrated a higher nocturnal diastolic BP dipping than regular day workers (19% vs. 17%, p = 0.03) and had a significantly higher systolic awake BP than regular day workers (136.5 mmHg vs. 132.5 mmHg, p = 0.03). Participants with high job demands demonstrated a smaller nocturnal systolic BP dipping than participants with low job demands (14% vs. 16%, p = 0.04). We did not observe significant differences in nocturnal systolic or diastolic BP dipping between groups categorized by occupational status or job control.

Conclusions

Although shift workers have a higher daytime BP than regular daytime workers, they exhibit greater nighttime BP dipping. Participants with high job demand had smaller nighttime BP dipping than participants with low job demand. Job control or occupation did not affect the 24-h ambulatory BP profile of aging workers.

Influence of quality of sleep in the first trimester on blood pressure in the third trimester in primipara women

Purpose: The purpose of this study was to clarify the relationship between decreased sleep quality during the first trimester and a rise in blood pressure during an otherwise normal course of pregnancy in primipara women. Materials and methods: We recruited 128 pregnant women (primipara) who visited the obstetrics and gynecology clinic for medical examination, of which 89 were longitudinally investigated from the first to the third trimester after obtaining informed consent. A survey was conducted in the first, second, and third trimesters to evaluate sleep quality using the Japanese version of the Pittsburgh Sleep Quality Index (PSQI-J). Patients were assigned to either a good sleep quality group (PSQI-J ≤ 5) or a poor sleep quality group (PSQI-J ≥ 6). Blood pressure was measured using a home blood pressure measurement method. We analyzed the relationship between sleep quality in the first trimester and blood pressure during pregnancy. Results: The increase in morning systolic blood pressure from first to third trimester was larger in the poor sleep quality group than in the good sleep quality group (7.1 ± 7.0 vs. 3.0 ± 5.6 mmHg, p < .01). Sleep latency (r = 0.38, β = 0.43, p = .02) and sleep disturbances (r = 0.24, β = 0.33, p = .04) in the first trimester affected the increase in systolic blood pressure during pregnancy. Conclusions: Understanding sleep quality at the beginning of pregnancy can help predict a rise in systolic blood pressure in the third trimester. This emphasizes the importance of sleep education during pregnancy.

Night blood pressure responses to atenolol and hydrochlorothiazide in black and white patients with essential hypertension

BACKGROUND

Night blood pressure (BP) predicts patient outcomes. Variables associated with night BP response to antihypertensive agents have not been fully evaluated in essential hypertension.

METHODS

We sought to measure night BP responses to hydrochlorothiazide (HCTZ), atenolol (ATEN), and combined therapy using ambulatory blood pressure (ABP) monitoring in 204 black and 281 white essential hypertensive patients. Initial therapy was randomized; HCTZ and ATEN once daily doses were doubled after 3 weeks and continued for 6 more weeks with the alternate medication added for combined therapy arms. ABP was measured at baseline and after completion of each drug. Night, day, and night/day BP ratio responses (treatment - baseline) were compared in race/sex subgroups.

RESULTS

Baseline night systolic BP and diastolic BP, and night/day ratios were greater in blacks than whites (P < 0.01, all comparisons). Night BP responses to ATEN were absent and night/day ratios increased significantly in blacks (P < 0.05). At the end of combined therapy, women, blacks, and those starting with HCTZ as opposed to ATEN had significantly greater night BP responses (P < 0.01). Variables that significantly associated with ATEN response differed from those that associated with HCTZ response and those that associated with night BP response differed from those that associated with day BP response.

CONCLUSIONS

In summary, after completion of HCTZ and ATEN therapy, women, blacks, and those who started with HCTZ had greater night BP responses. Reduced night BP response and increased night/day BP ratios occured with ATEN in blacks. Given the prognostic significance of night BP, strategies for optimizing night BP antihypertensive therapy should be considered.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT00246519.

Association between light exposure at night and nighttime blood pressure in the elderly independent of nocturnal urinary melatonin excretion

Circadian misalignment between internal and environmental rhythms dysregulates blood pressure (BP) variability because of disruption of the biological clock, resulting in increased nighttime BP. Although exposure to light-at-night is associated with the circadian misalignment, it remains unclear whether exposure to light-at-night in home settings is associated with nighttime BP. In this cross-sectional analysis of 528 elderly individuals (mean age: 72.8 years), we measured bedroom light intensity at 1-min intervals on two consecutive nights along with ambulatory BP, overnight urinary melatonin excretion and actigraphy. With regard to adjusted mean comparisons using analysis of covariance, the light-at-night group (average: ≥5 lux; n = 109) showed significantly higher nighttime systolic BP (SBP; adjusted mean: 120.8 vs. 116.5 mmHg, p = 0.01) and diastolic BP (70.1 vs. 67.1 mmHg, p < 0.01) compared with the Darker group (average: <5 lux; n = 419) independently of potential confounding factors including overnight urinary melatonin excretion and actigraphic sleep quality. We observed consistent associations between light-at-night and nighttime BP in different cutoff values for light-at-night intensity (i.e. 3 and 10 lux). In conclusion, exposure to light-at-night in home settings is significantly associated with increased nighttime BP in elderly individuals independently of overnight urinary melatonin excretion. A 4.3 mmHg increase in nighttime SBP is associated with a 6.1% increase in total mortality, which corresponds to approximately 10 000 annual excess deaths in Japanese elderly population.

Historical cohort study of shift work and blood pressure

BACKGROUND

It has been suggested that shift work (SW) is associated with changes in blood pressure (BP). However, studies have reported contradictory results.

AIMS

To prospectively examine the association between SW and BP among male workers.

METHODS

A historical cohort study, involving workers of Esfahan's Mobarakeh Steel Company, in Iran, was conducted over 14 years. The association between SW, systolic BP (SBP) and diastolic BP (DBP) was investigated after adjusting for body mass index, age, work experience, marriage, smoking and education based on the Bayesian multilevel modelling approach.

RESULTS

The study sample included 5331 male workers. The mean age (standard deviation, SD) was 34.8 (6.6) years and mean work (SD) experience was 9.4 (6.1) years. Among these subjects, 2348 (44%), 340 (6%) and 2643 (50%) were day workers, weekly rotating shift workers and routinely rotating shift workers, respectively. The mean SBP (SD) and DBP (SD) of these workers were 118.7 (8.1) and 73.1 (6.7) mmHg, respectively. After controlling for several confounding variables, there was no significant relationship between SBP and DBP and SW.

CONCLUSIONS

No significant association between SW and BP was observed among these three groups (day workers, weekly rotating shift workers and routinely rotating shift workers). Prospective studies, which control for confounding factors, such as the healthy worker effect, occupational history, family history and psychological factors (e.g. occupational stress and job satisfaction), are required to evaluate this further.

Melatonin in the afternoons of a gradually advancing sleep schedule enhances the circadian rhythm phase advance

RATIONALE

We test methods to advance (shift earlier) circadian rhythms without producing misalignment between rhythms and sleep. We previously tested (1) a gradually advancing sleep/dark schedule plus morning bright light and afternoon/evening melatonin and (2) the same sleep schedule with only morning bright light. Now we report on the same sleep schedule with only afternoon/evening melatonin.

OBJECTIVES

This study aims to examine phase advances, sleepiness, and performance in response to melatonin compared to placebo.

METHODS

Twelve adults (five female individuals) aged 20-45 years (mean ± SD = 28.3 ± 7.3 years) completed this within-subjects placebo-controlled counterbalanced study. The participants slept on fixed 8-h sleep schedules for nine days. Then, sleep/dark was advanced by 1 h/day for three consecutive days of treatment. The participants took 3 mg of melatonin or placebo 11 h before baseline sleep midpoint (the optimal time to produce phase advances) on the first treatment day and 1 h earlier on each subsequent day. We measured the dim light melatonin onset before and after treatment. The participants rated subjective symptoms throughout the study. They completed the Psychomotor Vigilance Task and rated sleepiness from 1 h before pill ingestion until bedtime on each treatment day.

RESULTS

Melatonin produced significantly larger advances (1.3 ± 0.7 h) compared to placebo (0.7 ± 0.7 h); however, in the hours between melatonin ingestion and bed, melatonin caused sleepiness and performance decrements.

CONCLUSIONS

Adding afternoon/evening melatonin to the gradually advancing sleep schedule increased the phase advance, but given the side effects, like sleepiness, it is better to use morning bright light and perhaps a lower dose of melatonin.

Shift work and cardiovascular risk factors: new knowledge from the past decade

Cardiovascular diseases remain a major public health problem. The involvement of several occupational factors has recently been discussed, notably the organization of work schedules, e.g. shift work. To analyse the progress of knowledge on the relationship between cardiovascular risk factors and shift work. A review of English-language literature dealing with the link between cardiovascular factors and shift workers (published during 2000-2010) was conducted. Studies published in the past 10 years tend to document an impact of shift work on blood pressure, lipid profile (triglyceride levels), metabolic syndrome and, possibly, body mass index. However, the consequences on glucose metabolism are unclear. These results are not yet firmly established, but are supported by strong hypotheses. Some advice could reasonably be proposed to guide the clinical practitioner.

Shift work is not associated with high blood pressure or prevalence of hypertension

Background

Working mostly at night has been suggested to be associated with upset of chronobiological rhythms and high blood pressure, but the evidence from epidemiological studies is weak.

Methods

In a cross-sectional survey, we evaluated the association between shift work and blood pressure, pre-hypertension and hypertension. In total, 493 nurses, nurse technicians and assistants, were selected at random in a large general hospital setting. Hypertension was diagnosed by the mean of four automatic blood pressure readings ≥140/90 mmHg or use of blood pressure lowering agents, and pre-hypertension by systolic blood pressure ≥120–139 or diastolic blood pressure ≥80–89 mmHg. Risk factors for hypertension were evaluated by a standardized questionnaire and anthropometric measurements. The association between the shift of work and blood pressure, pre-hypertension and hypertension was explored using univariate and multivariate analyses that controlled for risk factors for hypertension by covariance analysis and modified Poisson regression.

Results

The mean age of the participants was 34.3±9.4 years and 88.2% were women. Night shift workers were older, more frequently married or divorced, and less educated. The prevalence of hypertension in the whole sample was 16%, and 28% had pre-hypertension. Blood pressure (after adjustment for confounding) was not different in day and night shift workers. The prevalence of hypertension and pre-hypertension by shift work was not different in the univariate analysis and after adjustment for confounding (all risk ratios  = 1.0).

Conclusion

Night shift work did not increase blood pressure and was not associated with hypertension or pre-hypertension in nursing personnel working in a large general hospital.

Urinary melatonin and risk of incident hypertension among young women

OBJECTIVE

Administered in supraphysiologic doses, the hormone melatonin may reduce blood pressure, particularly nocturnal blood pressure. However, whether lower physiologic levels of melatonin are an independent risk factor for the development of hypertension has never been reported.

METHODS

We examined the association between first morning urine melatonin levels and the risk of developing hypertension among 554 young women without baseline hypertension who were followed for 8 years. Cox proportional hazards models were adjusted for age, BMI, physical activity, alcohol intake, smoking status, urinary creatinine, and family history of hypertension.

RESULTS

During 8 years of follow-up, a total of 125 women developed hypertension. The relative risk for incident hypertension among women in the highest quartile of urinary melatonin (>27.0 ng/mg creatinine) as compared with the lowest quartile (<10.1 ng/mg creatinine) was 0.49 (95% confidence interval 0.28-0.85, P < 0.001).

CONCLUSION

First morning melatonin levels are independently and inversely associated with incident hypertension; low melatonin production may be a pathophysiologic factor in the development of hypertension.

Prior exercise lowers blood pressure during simulated night-work with different meal schedules

BACKGROUND

Shift-work and a sedentary lifestyle are risk factors for raised blood pressure (BP). Exercise can reduce BP in diurnally-active individuals, but it is unknown whether postexercise hypotension persists when people are active and eating at night. We present the first investigation into the acute effects of exercise on BP monitored during simulated night-work.

METHODS

Nine normotensive participants, aged 20-42 years, completed at least two crossover trials beginning at 1800 hours. Between 1900 and 2000 hours, participants either rested or exercised at 50% peak oxygen uptake (VO(2peak)) and then remained awake throughout the night, completing various tasks until 0515 hours. Six participants completed a total of four trials in which they exercised or rested, whereas either one standardized (60 kJ/kg) meal at 2200 hours or two smaller (30 kJ/kg) meals at 2200 and 0200 hours were eaten. Systolic and diastolic BP, mean arterial pressure (MAP), heart rate (HR), and wrist activity were recorded every 30 min.

RESULTS

Following exercise, MAP was significantly (P < 0.0005) lower throughout the night-shift compared with no prior exercise (95% confidence limits for reduction: 4-7 mm Hg). The postexercise reductions in systolic BP and MAP were not moderated by diet, but the reduction in diastolic BP was slightly greater when only one meal was eaten (P < 0.0005). BP was lower even though wrist activity and HR were significantly higher following exercise (P < 0.0005).

CONCLUSIONS

These data indicate that prior exercise lowers BP throughout a subsequent 8-h night-shift in healthy individuals within the normotensive range. Therefore, regular low-intensity exercise might moderate the well-known association between shift-work participation and raised BP.