Associations between diurnal 24-hour rhythm in ambulatory heart rate variability and the timing and amount of meals during the day shift in rotating shift workers

Reduced heart rate variability is related to fluctuations in psychological stress levels in daily life

Laboratory-based studies have shown that psychological stress caused by response to various stressors triggers acute changes in the cardiovascular system. A better understanding is needed of the emerging evidence on temporal associations between psychological stress and cardiovascular responses in natural settings. This study examined the association of psychological stress and heart rate variability (HRV) in daily life, at high resolution over 2 weeks, taking the effect of physical activity into account. Participants (n = 34) completed ecological momentary assessments (EMA) 6 times per day, reporting levels of perceived stress, low-arousal negative affect (LNA), and high-arousal negative affect. Chest-mounted heart-rate monitors were worn to assess HRV. Multilevel models were used to examine the association between psychological stress levels and preceding/subsequent HRV. Reduced time domain HRV measures (mean and standard deviation of R-wave to R-wave intervals) during the prior hour predicted higher levels of perceived stress. Frequency domain HRV measures higher low to high frequency (LF/HF) and lower HF to total power (HF nu) ratios during the preceding 10 min predicted higher perceived stress levels, suggesting the dominance of sympathetic nervous system activity. EMA reports of higher perceived stress levels were associated with reduced time domain HRV measures during the following 10 min. On the other hand, higher LNA were related to increased HRV measures, such as lower LF/HF and higher HF nu during the following hour. The dynamic associations observed may have therapeutic implications for 'just-in-time' interventions in the management of daily stress and cardiovascular health.

Benefits of Mediterranean and Japanese Diets among Nurses: A Scoping Literature Review

INTRODUCTION

The present study aimed at all the benefits induced by taking the Mediterranean or Japanese diet among nurses and whether any beneficial differences in intakes between the two diets were considered.

METHODS

The author searched PubMed and Embase databases for medical subheadings terms and free full text referring to "Diet," "Mediterranean," "Japanese," and "Nurses" before 31st December 2022.

RESULTS

A total of 14 studies were included in this scoping review, which better underlined all the benefits implicated in the Mediterranean or Japanese diets assumption and also if there were any differences between the two diets. These eating behaviors were exclusively investigated among nurses.

CONCLUSION

The nursing profession has always been considered the most stressful healthcare activity. However, some important concerns in the regular lifestyle, such as eating and physical activity, might help to live better.

A Pilot Study of Temporal Associations Between Psychological Stress and Cardiovascular Response

Psychological stress (PS) in daily life can trigger acute changes in cardiovascular function and may lead to increased risk of cardiovascular problems. Prior laboratory-based studies provide little evidence on temporal changes in the associations between PS and cardiovascular responses in natural settings. We hypothesized that daily PS would be associated with higher heart rate (HR) and lower heart rate variability (HRV). Using smartphones, ten participants (four females, 21.1±1.1 years) completed ecological momentary assessment (EMA) 6 times a day for two weeks regarding their current affective state. Participants rated levels of PS, as well as 3 high-arousal negative affect (HNA: Anxious, Annoyed, and Upset), and 3 low-arousal negative affect (LNA: Sluggish, Bored, and Sad) states. They also wore a chest-mounted heart-rate monitor and a wrist accelerometer to monitor cardiovascular response and physical activity, respectively. HR and HRV variables in the time intervals (5, 30, 60 min) before and after EMA were used as indicators of cardiovascular response. Multilevel modeling was used to examine the association between affect and HR/HRV, controlling for physical activity. Higher HR and lower HRV were related to subsequent greater feelings of stress at the 5 and 30-min time intervals. No significant associations were observed between cardiovascular parameters and subsequent affective states, suggesting that the acute exaggerated cardiovascular responses occurred due to PS. Higher LNA was related to antecedent/subsequent lower HR or higher HRV within 2 hours, while HNA was unrelated to HR or HRV for all time intervals, suggesting that both high/low arousal NA were not related to exaggerated cardiovascular response. Understanding psychological feelings of stress and LNA may be helpful in the management of daily cardiovascular health.

Association between depressive symptoms and morningness-eveningness, sleep duration and rotating shift work in Japanese nurses

Higher depressive symptoms have been reported in rotating shift workers compared with day workers. Depressive symptoms in adults who do not engage in night work have also been shown to be associated with chronotype and sleep duration. This study examines associations between depressive symptoms, morningness-eveningness (i.e. the degree to which people prefer to be active in the morning or the evening), sleep duration and rotating shift work. Japanese nurses (1252 day workers and 1780 rotating shift workers, aged 20-59) were studied using a self-administered questionnaire. The questionnaire covered depressive symptoms, morningness-eveningness, sleep habits and demographic characteristics of the participants. The Center for Epidemiologic Studies Depression Scale (CES-D) was used to determine the levels of depressive symptoms. A Japanese version of the Morningness-Eveningness Questionnaire (MEQ) was used to measure morningness-eveningness. The CES-D score of shift workers was significantly (p < 0.05) higher than that of day workers. The MEQ score was significantly (p < 0.05) lower (i.e. greater eveningness) in shift workers than in day workers. Sleep duration on the day shift was significantly (p < 0.05) shorter in shift workers than in day workers. Simple linear regression revealed that the MEQ score, sleep duration on the day shift and current work shift (i.e. rotating shift work) were significantly (p < 0.05) associated with the CES-D score. Multivariate linear regression indicated that greater eveningness and shorter sleep duration were independently associated with higher CES-D scores, while rotating shift work was not. These associations between the MEQ score, the sleep duration and the CES-D score were also confirmed in both day workers and shift workers when the groups were analyzed separately. These results suggest that greater eveningness and shorter sleep duration on the day shift were independently associated with higher levels of depressive symptoms, which may explain associations between rotating shift workers and depressive symptoms. These findings have important implications for the development of novel strategies for preventing poor mental health in day workers and rotating shift workers.

Association of eating behaviours with diurnal preference and rotating shift work in Japanese female nurses: a cross-sectional study

OBJECTIVES

Our study examines differences in eating behaviour between day workers and rotating shift workers, and considers whether diurnal preference could explain the differences.

METHODS

Japanese female nurses were studied (39 day workers and 123 rotating shift workers, aged 21-63 years) using self-administered questionnaires. The questionnaires assessed eating behaviours, diurnal preference and demographic characteristics. The questionnaire in the Guidelines for the management of obesity disease issued by the Japan Society for the Study of Obesity was used to obtain scores for the levels of obesity-related eating behaviours, including cognition of constitution, motivation for eating, eating as a diversion, feeling of satiety, eating style, meal contents and temporal eating patterns. The Japanese version of the Morningness-Eveningness (ME) questionnaire was used to measure self-rated preference for the degree to which people prefer to be active in the morning or the evening (ME).

RESULTS

The scores for meal contents and temporal eating patterns in rotating shift workers were significantly higher than those in day workers. The ME score of rotating shift workers was significantly lower, indicating greater eveningness/less morningness among rotating shift workers. Multivariate linear regression revealed that the ME score was significantly negatively associated with temporal eating patterns and showed a negative association with the score for meal contents at a trend level, while current work shift was not significantly correlated with the scores.

CONCLUSIONS

These results suggest that eating behaviours for rotating shift workers are associated with a more unbalanced diet and abnormal temporal eating patterns and that the associations may be explained by diurnal preference rather than by rotating shift work.

Heart rate variability is associated with interstitial glucose fluctuations in type 2 diabetic women treated with insulin

Heart rate variability (HRV) analysis is a commonly used tool for assessment of autonomic function in diabetic subjects. Nevertheless, the effects of glucose fluctuations on HRV remain to be clarified. In this study we investigated the associations of frequency-domain HRV parameters with current and antecedent interstitial glucose fluctuations in insulin-treated type 2 diabetic women at high cardiovascular risk. Sixty-seven women with type 2 diabetes, from 48 to 78 years of age, including 46 ones with cardiovascular autonomic neuropathy (CAN), underwent simultaneous continuous glucose monitoring (CGM) and Holter recording. Eight glucose variability (GV) indices, including standard deviation, 2-h continuous overlapping net glycemic action (CONGA2), lability index, J-index, mean amplitude of glucose excursions, mean absolute glucose (MAG), low blood glucose index (LBGI) and high blood glucose index (HBGI), were calculated from CGM data. The low frequency (LF) and high frequency (HF) power values were estimated on 5-min intervals at fasting and postprandial daytime periods, at night and during CGM-defined hypoglycemia. The values of LF and HF power declined after meals in diabetic women with normal autonomic function tests. Patients with CAN demonstrated blunted postprandial LF and HF reduction and diminished LF/HF ratio during daytime hypoglycemic events. Daytime LF and HF at fasting state correlated negatively with MAG derived from antecedent nocturnal CGM recordings. Positive correlation was found between fasting LF and nocturnal LBGI. The LF power during daytime hypoglycemia demonstrated negative correlations with nocturnal CONGA2, J-index, HBGI and MAG. The nocturnal HBGI and CONGA2, along with HbA1c and daily insulin dose, were predictors of LF during daytime hypoglycemia in multiple regression analysis. Both postprandial and antecedent nocturnal glucose fluctuations affect daytime frequency-domain HRV parameters in insulin-treated type 2 diabetic women. In patients with increased GV the results of short-term assessment of HRV should be interpreted with caution. Fasting state rather than postprandial one seems to be preferable for HRV estimation.