Chang SJ, et al. Korean J Occup Environ Med. 2005 Dec;17(4):297-317. https://doi.org/10.35371/kjoem.2005.17.4.297

Despite the increasing demands of ultra-short-term heart rate (HR) variability (HRV) for practical ambulatory applications, there have been few studies that have investigated R-R interval recording for less than 5 min for HRV analysis. It has not been extensively validated, and, currently, no normative data for ultra-short-term HRV exist. The aim of this study was to investigate the relationship between standard 5-min and ultra-short-term HRV by collecting data from a large population consisting of a wide range of age groups. The 5-min R-R interval series were obtained from 467 healthy volunteers ranging from 8 to 69 years of age. The original R-R interval was segmented into 270, 240, 210, 180, 150, 120, 90, 60, 30, 20, and 10 s, and those HRV features most commonly reported within the literature were calculated and compared with those using the original 5-min R-R interval series. The Pearson correlation r, the p value by the Kruskal-Wallis test, and the Bland-Altman plot analysis computations were performed for each HRV variable calculated using different lengths of R-R interval series. For each HRV variable, the minimum length of the R-R interval required to reliably estimate the 5-min HRV was identified. The results were different for each age group: 10 s for HR, 20 s for high-frequency, 30 s for root mean square difference, 60 s for proportion of the number of interval differences of successive NN intervals greater than 50 ms divided by total number of NNs, 90 s for low-frequency, normalized low-frequency, normalized high-frequency, and low-frequency/high-frequency, 240 s for standard deviation of successive NN interval differences and time-frequency, and 270 s for very low-frequency. In addition, the reference value for short-term HRV from normal healthy subjects was also presented. Some HRV variables calculated from R-R interval series shorter than 5 min were well matched with those calculated from the 5-min R-R interval. Thus, ultra-short-term HRV is likely to be a good surrogate method to assess trends in HRV.

A seasonal suicide peak in spring is highly replicated, but its specific cause is unknown. We reviewed the literature on suicide risk factors which can be associated with seasonal variation of suicide rates, assessing published articles from 1979 to 2011. Such risk factors include environmental determinants, including physical, chemical, and biological factors. We also summarized the influence of potential demographic and clinical characteristics such as age, gender, month of birth, socioeconomic status, methods of prior suicide attempt, and comorbid psychiatric and medical diseases. Comprehensive evaluation of risk factors which could be linked to the seasonal variation in suicide is important, not only to identify the major driving force for the seasonality of suicide, but also could lead to better suicide prevention in general.

This study aimed to investigate the effects of a two-day forest therapy program on individuals with chronic widespread pain. Sixty one employees of a public organization providing building and facilities management services within the Seoul Metropolitan area participated in the study. Participants were assigned to an experimental group (n = 33) who participated in a forest therapy program or a control group (n = 28) on a non-random basis. Pre- and post-measures of heart rate variability (HRV), Natural Killer cell (NK cell) activity, self-reported pain using the visual analog scale (VAS), depression level using the Beck Depression Inventory (BDI), and health-related quality of life measures using the EuroQol Visual Analog Scale (EQ-VAS) were collected in both groups. The results showed that participants in the forest therapy group, as compared to the control group, showed physiological improvement as indicated by a significant increase in some measures of HRV and an increase in immune competence as indicated by NK cell activity. Participants in the forest therapy group also reported significant decreases in pain and depression, and a significant improvement in health-related quality of life. These results support the hypothesis that forest therapy is an effective intervention to relieve pain and associated psychological and physiological symptoms in individuals with chronic widespread pain.

Objective: This article aimed to develop the “forest therapy” program, which is a cognitive behavior therapy (CBT)-based intervention program using forest environment, and investigate its effects on blood pressure (BP), salivary cortisol, and quality of life (QoL) measures in patients with hypertension. Methods: A total of 56 men and women were enrolled for this study, being referred from local health centers in Republic of Korea, from April to October 2009. They were conveniently assigned to either “forest” group participating in the forest therapy program or control group doing self-monitoring of BP. Measurements of salivary cortisol level and QoL were done at initial visits and at 8-week final visits. Results: Both groups did not differ significantly in baseline clinical characteristics. The BP change at week 4 and week 8 did not differ between the two groups. Salivary cortisol level reduction was significantly larger and QoL measures improved significantly more in the forest group at week 8 compared with the control group. Conclusions: The forest therapy program did not induce prolonged systolic blood pressure (SBP) reduction. However, considering the significant decrease in cortisol level and improvement in QoL measures, this may be a useful model of community hypertension management program.

The purpose of this paper is to review the evidence estimating an impact of occupational factors on mood disorders and suicide, and the efficacy of interventions. This review is based on literature searches using Medline and Psych INFO from 1966 to 2007 (keywords: work stress, job insecurity, job strain, shift work, violence, occupational health, mood disorders, depression, and suicide). To establish the relationship between occupational variables and mood disorders, we focused on clinically significant disorders rather than depressive symptoms. During the last decade, prospective epidemiological studies have suggested a predictive association between the work environment and mood disorders. Recently, increasing numbers of clinical trials have shown favorable effect size of intervention and suggested preferable return-on-investment results. However, low awareness and social stigma still decrease workers access to treatment. Mental health professionals in conjunction with employers have to devise a creative system to make the quality care being offered more accessible to employees. In addition, further outcome data is needed to evaluate the benefit of managing mood disorders in the workplace, and to foster awareness of positive implications for employees, employers, their families, and the society at large. In addition, the work environment, with its chemical (e.g. chemosensory factors, pollutants), physical (e.g. lighting, noise, temperature, outdoor views and activities), biological (e.g., chronobiological factors, allergens, infectious agents), psychological (e.g. demand-control, effort-reward balance), social (e.g. cohesiveness, support), and organizational (e.g. leadership styles) component should meet minimal standards, and may improve with striving towards the optimum.