Does Forest Contemplation Provide Greater Psychological Benefits than Passive Exposure to the Urban Forest? A Pilot Study

Abstract

Human contact with the natural environment effectively counteracts negative symptoms of stress and has many positive psychological effects. For this reason, forests within city limits are increasingly seen as part of public health promotion. Being in an urban forest can take many forms, but there is still little known about whether being in a forest alone, without engaging one’s senses, is as effective for human renewal as an experience that involves greater, more conscious activation of the senses of sight, hearing, smell. A study measuring the effect of the forest (spring aspect) on human mental relaxation during passive exposure was conducted on a sample of 19 Polish young adults. The experiment consisted of two series. In the first, participants read an academic textbook in a tree stand for 20 min, while in the next session—conducted at the same location—they contemplated the landscape. Before the experiment and after each of the two series of tests, four psychological questionnaires were administered: the Profile of Mood State (POMS), Positive and Negative Affect Schedule (PANAS), the Restorative Outcome Scale (ROS) and the Subjective Vitality Scale (SVS). Analyses showed that being in a forest environment positively influenced the subjects’ mental relaxation, while the level of benefit from the activation of the senses, especially vision (looking at the forest) was significantly higher compared to the passive activity of reading a text. The research indicates that forest bathing is the best form of relaxation that can be obtained through contact with the forest.

1. Introduction

1.1. The Deficit of Nature

Today, the main health problem of the 21st century is non-communicable diseases (NCDs) [1,2]. More than 85% of all deaths and 75% of all diseases in Europe can be associated with the NCD group [3]. The five “major” non-communicable diseases (NCDs) [4,5] are considered to be cardiovascular disease (CVD) [6,7], diabetes [8], cancer [9], chronic respiratory diseases [10] and, more recently, mental disorders, including depression [11,12]. Risk factors influencing the occurrence of non-communicable diseases include tobacco use, harmful alcohol consumption, unhealthy diet, low physical activity and exposure to environmental pollutants, primarily air pollution. In recent years, limited contact with nature, referred to as nature-deficit syndrome, has been added to the group of these factors. The disorders resulting from this have been recognized by Louv [13] as a worrying non-communicable disease of modern urban societies. He introduced nature-deficit disorder to the literature; this is not a medical entity, but refers to serious changes in the psyche, health troubles and social problems of people of all ages [14,15]. High urbanization of cities, degradation of natural landscapes, prevalence of digitization, limited activity of children in natural areas, limited leisure time among families or insufficient environmental education are cited as the main causes of nature deficit in both scientific and popular literature [16,17].

People’s contact, especially that of residents of large cities, with the natural environment, effectively counteracts negative symptoms of stress, and has many positive psychological effects. There is abundant scientific evidence indicating that physical activity in the forest or exposure to the forest landscape plays an important role in the regeneration of the human body [18,19]. Numerous studies have examined the regenerative properties of the forest environment undertaken as a result of recreational activities [19,20,21,22,23,24,25]. There is already ample evidence that nature can help people rebuild and regenerate psycho-physical forces [18,26,27,28]. Bringing nature back into our lives is so important that it forms the core of the name of one of the important documents setting the framework for EU policy, which is the Biodiversity Strategy 2030 [29]. The very first pages of this document state that nature is as important for people’s physical well-being and mental health as it is for society’s ability to cope with global change, health risks and disasters. The continuation and detailing of the European Green Deal [30], including social health, can be found in another EU document directly related to forests, namely the New EU Forestry Strategy 2030 [29]. The very first sentence of this document states that forests and other wooded areas are essential for the health and well-being of all European people. They provide a place where people can feel close to nature, and strengthen their physical and mental health. For this reason, forests within city limits are increasingly seen as part of the promotion of public health [31,32,33].

1.2. The Role of Urban Greenery in Ensuring Human Health and Well-Being

The role of urban greenery is growing, due to the progressing urbanization of space [34]. It is estimated that by 2030, over 80% of Europe’s population will live in urban areas; it will therefore be up to city leaders to promote health and well-being [35]. Urban greenery, particularly forests, provides opportunities for everyday recreation, physical activity, mental restoration, and social meeting. The extent or frequency of use of public urban forests is mediated by the relative ease of access, either physically or financially, as well as the quality of the green areas [17,21]. Being in an urban forest can take many forms, engaging human senses to varying degrees. Despite growing evidence of the positive impact of the forest on human health and well-being, there are still many unknowns about the level of benefits experienced in relation to the intensity of forest management, the features of the forest landscape, or the form of physical activity. There is also a lack of knowledge about the impact of forests on people, depending on the season. Knowledge of the impact of forests on people in different seasons is needed, especially in those regions where there are different seasons and where different conditions exist in forests, resulting in trees losing their leaves in autumn and failing to keep their leaves in winter (deciduous forests). Many previous studies have been undertaken in winter [21,36,37] and autumn [38,39]. There were also studies comparing spring with other seasons. For example, Takayama et al. [40] compared spring benefits with those obtained in autumn, and Bielinis et al. [41] analyzed which season (winter vs. spring) is better for forest bathing interactions and which environment is better for reducing stress symptoms. There is also still not much known about whether just being in the forest without engaging the senses is as effective for human renewal as one that involves greater, more conscious activation of the senses of sight, hearing, and smell.

1.3. Objective and Hypotheses

The purpose of our experiment is to compare the level of physiological and psychological benefits achieved by two variants of passive exposure to the forest (no physical activity), characterized by varying degrees of sensory activation. We decided to conduct the study among young people, because there are many studies that show that this group is most vulnerable to stress [42]. We carried out the study in spring, due to the fact that at this time of year the forest is particularly lively in terms of bird sounds, and moreover, this time of year has not often been included in studies on the effects of the forest on relaxation.

The hypotheses formulated for the study are as follows (Figure 1):

• Being in a forest environment has a positive effect on the psychological relaxation of the subjects.
• The relaxation effect achieved as a result of the activation of the senses, especially the sense of sight (looking at the forest), is significantly higher compared to the activity limiting the possibility of contemplating the forest.

2. Materials and Methods

2.1. The Theoretical Framework of the Work

The study is expected to be a single-group, within-subjects, repeated-measures design. The theoretical location plane of the work is, on the one hand, Wilson’s Biophilia Concept [43,44], which suggests that humans have an innate tendency to connect with other life forms and nature. According to this theory, contact with nature is not only enjoyable, but essential to mental and physical health. The second theoretical concept is that of forest bathing. The term forest bathing was coined in 1982 by the Ministry of Agriculture, Forestry and Fisheries of Japan [45]. Forest therapy involves attentively communing with nature through the “experience of the five senses” (sight, smell, hearing, touch and taste) when the body is exposed to the forest environment [31,46]. Figure 2 graphically explains the methodology used to obtain information, from theoretical perspectives to methodological strategies.

2.2. Participants

The study involved 19 volunteers from among the students of the Warsaw University of Life Sciences, who had no known chronic illness and did not show any visible signs or symptoms of disease. There were 12 men and 7 women aged 20–24. Participants were familiarized with the objectives, procedures and methods of the study in which they participated. Participants were not allowed to communicate with other participants or researchers during the forest observation (approximately 20 min) or while completing psychological test questionnaires (approximately 15 min). In addition, participants were not allowed to use cell phones, drink alcoholic and caffeinated beverages, or smoke cigarettes. The psychological questionnaires used in the study were anonymous. Participants and researchers used pseudonyms. Immediately after completion of the forms by the participants, they were checked by the study supervisors for completeness. All actions taken during the study were in line with the ethical standards of the Polish Committee of Ethics in Science and the Declaration of Helsinki of 1964 (with changes), as amended.

2.3. Study Sites

The survey was conducted in May 2023 (11 May 2023) in the Kabaty Forest, the largest forest in Warsaw, consisting of more than 900 ha—Figure 3. The species composition is dominated by oak trees (70%) aged 64 years, accompanied by pine (20%) and birch (10%). The undergrowth contains hornbeam, oak, and linden. Species mixing is grouped, stand density is moderate, and cover is green (https://www.bdl.lasy.gov.pl/portal/mapy-en; accessed on 16 April 2023). The habitat type of the forest is fresh forest. The meteorological data in effect at the time of the experiment were determined using data from the nearest meteorological station—the Meteo Station of the Warsaw University of Life Sciences, located at an altitude of 100 m above sea level (location: 52°09′37.37′′ N 21°03′11.92′′ E). The average daily temperature was 14.6 °C (maximum 19.07 °C, minimum 4.01 °C), the relative humidity was 33%–62%, the average cloudiness was 5.3 (on the octane scale), the atmospheric pressure was 1008 hPa, and the wind speed was up to 8.3 m/s. Noise and sunlight levels were controlled during the experiment. Sound and light levels were also measured with an iPhone 12 using the LUX Light Meter FREE and Sound Level Analyzer Lite applications. Similar applications have been used in other studies by Tsunetsugu et al. [47] and Janeczko et al. [16], and they meet standards comparable to professional laboratory equipment for sound analysis. Sound and light were measured at each exposure point before, 2 times during, and immediately after completing the psychological test questionnaire. The average sound level measured with the sound level meter amounted to 38.4–49.9 dB. The mean light intensities in the forest amounted to 2208–2513 lx.

2.4. Procedure

The experiment began at 10 a.m. Every hour, 4 participants in the experiment met with researchers on a recreational meadow in the Kabaty Forest. The participants were informed of the procedure of the experiment and the rules in force. Each group, along with a researcher guide, went to the forest for the next stage of the experiment. The walking time from a recreational meadow to the forest is approximately 5 min. The participants did not undertake any physical activity on the site, in the forest stand. They sat on deckchairs. At this point, they were asked to answer questions on psychological test questionnaires. Blood pressure and pulse measurements were also taken. The next step (passive exposure stage) was to give the participants academic textbooks with a marked forestry text for independent study. According to the instructions, after the time allotted for reading the text had elapsed (20 min), participants answered, in writing, several questions referring to the text they had read. Participants in the experiment were informed that their way of answering the questions (extremely simple) would not be formally assessed. Follow-up questions were only asked to ensure that the research participants had really read the book. Failure to answer a question correctly meant that the participant had not followed the instructions (had not read the book with understanding) and their change in mood could not be taken into account when analyzing the results of the study. It was felt that this type of control was necessary, and it was accepted that it could cause minimal stress. However, in the end there was no need to exclude anyone from the study. We then measured the blood pressure and pulse rate of the participants in the experiment. Participants also completed the POMS, PANAS, SVS, and ROS psychological tests. The next stage (forest contemplation stage) of the experiment consisted of respondents sitting in recliners and looking at the forest for 20 min, without engaging in any other activity and then, using psychological tests, information was collected on the emotional state and mood of study participants; participants’ blood pressure and pulse rate were monitored during the study. The general scheme of the procedure is shown in Figure 4.

2.5. Measurements

Four psychological questionnaires were used in the experiment:

• The Polish version of the scale of D. Watson and L.A. Clark’s positive and negative affect schedule developed by Brzozowski (PANAS) [42], consisting of 20 questions, ten of which are about positive feelings and ten about negative feelings. Each question is rated on a five-point Likert scale (1—strongly disagree to 5—strongly agree). The Positive and Negative Affect Schedule (PANAS) questionnaire includes two different scales. One of them measures positive affect (PA), and the other measures negative affect (NA). Based on results obtained before (PAPRE, NAPRE) and after (PAPOST, NAPOST) experimental exposure, the beneficial change of positive (ΔPA = PAPOST − PAPRE) and the beneficial change of negative (ΔNA = NAPRE − NAPOST) affect were calculated. The reliability and accuracy of the PANAS questionnaire are high, something which has been confirmed in many studies [25].
• The Restorative Outcome Scale (ROS), containing six items, each of which was rated by participants using a seven-point Likert scale (1—strongly disagree to 7—strongly agree), was used sequentially. This scale, developed by Korpela [48] and adapted into Polish by Bielinis et al. [21], is a single-scale questionnaire, which measure subjective feelings of mental restoration. Based on results obtained before (ROSPRE) and after (ROSPOST) experimental exposure, the beneficial change in these specific dimensions of psychological well-being (ΔROS = ROSPOST − ROSPRE) was calculated as differential data.
• Next, the Subjective Vitality Scale (SVS) was used to assess vitality. It reflects a sense of energy, vitality, and well-being (e.g., “I feel alive and vital” or “I look forward to each new day”). The four items were rated by participants using a seven-point Likert-type scale (1—very unlikely to 7—very likely). Based on results obtained before (SVSPRE) and after (SVSPOST) experimental exposure, the beneficial change in these specific dimensions of psychological well-being (ΔSVS = SVSPOST − SVSPRE) was calculated as differential data. This scale has been used in previous studies, thereby confirming its effectiveness [49].
• The last scale was the Profile of Mood State (POMS) scale. The Polish adaptation of the questionnaire was developed by Dudek and Koniark [50]. This questionnaire includes six different subscales of mood state: Tension (T), Anger (A), Fatigue (F), Depression (D), Confusion (C) and Vigor (V). A five-point Likert scale was used for each question to rate participants’ mood states from 0 (strongly disagree) to 4 (strongly agree). A total mood disturbance (TMD) score can also be calculated using POMS data (TMD = T + D + A − V + F + C). Based on results obtained before (TPRE, APRE, FPRE, DPRE, CPRE, VPRE, TMDPRE) and after (TPOST, APOST, FPOST, DPOST, CPOST, VPOST, TMDPOST) experimental exposure, the beneficial change in six different dimensions of mood (ΔT = TPRE − TPOST, ΔA = APRE − APOST, ΔF = FPRE − FPOST, ΔD = DPRE − DPOST, ΔC = CPRE − CPOST, and ΔV = VPOST − VPRE) was calculated. Moreover, the beneficial change in the total mood disturbance (ΔTMD = ΔT + ΔD + ΔA + ΔV + ΔF + ΔC) was calculated as differential data. The POMS is a reliable and contemporary measure of mood state, previously used to assess the impact of the forest environment on the moods of individuals [39,51].

In addition, three physiological parameters were measured: diastolic (DIA) and systolic (SYS) blood pressure and pulse (heart rate—HR). Parameters were measured using Omron m2 basic automat blood pressure monitor. Based on results obtained before (DIAPRE, SYSPRE, HRPRE) and after (DIAPOST, SYSPOST, HRPOST) experimental exposure, the beneficial change in the aforementioned parameters (ΔDIA = DIAPRE − DIAPOST, ΔSYS = SYSPRE − SYSPOST, and ΔHR = HRPRE − HRPOST) was calculated as differential data.

2.6. Data Analysis

All raw data were stored in Excel (Microsoft 2019, version 1808, Redmond, WA, USA), and mean values, as well as standard deviation (SD) values, were calculated using this program. Further analysis was performed using STATISTICA version 13.3 (TIBCO Software Inc., Palo Alto, CA, USA). The Student’s t-test (t-test) was used to check the differences between the respondents’ mean answers for dependent samples. The assumption of normality of the distribution of variables was formally verified (using the Shapiro–Wilk test) before these analyses were performed.

2.7. Justification of Sample Size

A small pilot study with a small number of subjects was planned. For organizational reasons, it was considered best that the number should not exceed 20 people. In planning the study, an attempt was made to theoretically test whether such a small sample size would allow for a sufficiently high level of power of the one-sample t-test (i.e., at least 0.8, and preferably over 0.9). It is generally known that the power test depends not only on the sample size but also on the following: the type of hypothesis (a non-directional hypothesis was adopted for each variable), the level of significance (a standard value of 0.05), the expected standard deviation (approximate values were taken for each variable, which were estimated on the basis of previous, both published and as yet unpublished research by the authors, conducted under analogous conditions), and the expected level of difference in means that one plans to detect (these values were taken separately for each variable with their standard deviations, i.e., controlling for Cohen’s d effect size). To determine the minimum sample size, the standard tool Power Analysis available in the IBM SPSS package was used (specifically, IBM SPSS Statistics 29 was used). After conducting the relevant analysis, it was found that a sample size of 19 was sufficient to obtain a power of the one-sample t-test above 0.9, with the assumptions shown in

Table 1. Detailed assumptions made for Power Analysis (using IBM SPSS Statistics 29).

Name of the Measured Variable	Expected, Approximate Value of Standard Deviation Estimated on the Basis of Previous Own Research Conducted in Analogous Conditions	The Difference in Mean That Can Be Detected by a One-sample t-Test Assuming a Test Power above 0.9 (Cohen’s d Effect Size)	Power of One-Sample t-Test for Non-Directional (Two-Sided) Analysis
ΔSYS	10	8 (0.8)	0.909
ΔDIA	10	8 (0.8)	0.909
ΔHR	5	4 (0.8)	0.909
ΔPA	0.5	0.4 (0.8)	0.909
ΔNA	0.5	0.4 (0.8)	0.909
ΔROS	1	0.8 (0.8)	0.909
ΔSVS	1	0.8 (0.8)	0.909
ΔT	0.5	0.4 (0.8)	0.909
ΔD	0.25	0.2 (0.8)	0.909
ΔA	0.4	0.32 (0.8)	0.909
ΔF	0.5	0.4 (0.8)	0.909
ΔC	0.5	0.4 (0.8)	0.909
ΔV	0.5	0.4 (0.8)	0.909

.

What draws attention in Table 1 is the large value of Cohen’s d effect size (0.8). This means that the adopted sample size is small enough to effectively detect only relatively large differences in averages, which is quite typical for pilot studies. Of course, this does not mean that it is not possible to detect more subtle differences, but it is more difficult, because in such cases the power of one-sample t-test is reduced.

3. Results

3.1. Physiological Indices

The average values of basic physiological benefits with their expanded uncertainty intervals (with a confidence level of 95%) observed for each of the two tested types of exposure are presented in Figure 5 (∆HR) and Figure 6 (∆DIA and ∆SYS).

Based on statistical analysis (Figure 5) (t-test in Statistics), it was found that change in heart rate (ΔHR) was statistically significant for forest exposure and for results obtained in total for “contemplation of the forest” and “passive” exposure. An additional statistically significant, although unfavorable, phenomenon was an increase in diastolic blood pressure for “passive” exposure. This is evidenced by the clearly negative value of beneficial change in diastolic pressure (DIA). Other changes in measured physiological parameters did not prove statistically significant (

Table 2. Means, standard errors of the means, and t-test results of psychological measures of diastolic and systolic blood pressure and pulse during the experiment.

Measures	Forest Contemplation			“Passive” Exposition			Total
	Mean (Std. Error)	T	p	Mean (Std. Error)	T	p	Mean (Std. Error)	T	p
ΔSYS	2 ± 5.1 (2.55)	0.78	0.445	−3 ± 4.8 (2.4)	−1.26	0.226	−0.5 ± 3.5 (1.75)	−0.28	0.78
ΔDIA	3.17 ± 3.2 (1.6)	1.99	0.063	−5.3 ± 3.6 (1.8)	−2.98	0.008 *	−1.1 ± 2.8 (1.4)	−0.79	0.438
ΔHR	5.5 ± 2.6 (1.3)	4.22	0.001 *	2.5 ± 3.2 (1.6)	1.57	0.135	4 ± 2.1 (1.05)	3.83	0.001 *

* statistically significant difference (p < 0.05).

).

Using the data in Table 2, the overall (cumulative) blood pressure change (ΔBP = ΔSYS + ΔDIA) was calculated. The average values of this overall index are shown in Figure 7. The only statistically significant phenomenon in this case was an unfavorable increase in cumulative blood pressure for “passive” exposure (ΔBP = −8 ± 6).

3.2. Psychological Indices

3.2.1. Positive and Negative Affect Schedule (PANAS)

Reliability—the internal consistency coefficient for the PANAS scale established on the basic of data obtained was 0.839 (PANAS negative) and 0.884 (PANAS positive). The average values of benefits (ΔPA, ΔNA) with expanded uncertainties (with a 95% confidence level) that were observed for each of the two groups tested are shown in Figure 8. Based on statistical analyses (t-test in Statistics), a statistically significant increase in positive affect was observed for forest exposure and for total results (obtained in total for “contemplation of the forest” and for “passive” exposure). All other changes in PANAS results did not prove to be statistically significant (

Table 3. Means, standard errors of the means and t-test results of psychological measures of PANAS during the experiment.

Measures	Forest Contemplation			“Passive” Exposition			Total
	Mean (Std. Error)	t	p	Mean (Std. Error)	t	p	Mean (Std. Error)	t	p
ΔPA	0.38 ± 0.24 (0.12)	3.17	0.005 *	−0.02 ± 0.22 (0.11)	−0.14	0.89	0.18 ± 0.17 (0.085)	2.11	0.04 *
ΔNA	0.13 ± 0.3(0.15)	0.89	0.39	0.12 ± 0.18 (0.09)	1.31	0.21	0.13 ± 0.17 (0.085)	1.47	0.15

* statistically significant difference (p < 0.05).

).

Based on the data in Table 3, the overall, cumulative affect improvement (ΔPANAS = ΔPA + ΔPN) was calculated. The average values of this overall index are shown in Figure 9. Statistically significant improvement in emotional state was observed for contemplation of the forest (ΔPANAS = 0.5 ± 0.4) and for results obtained in total for forest contemplation and “passive” exposure (ΔPANAS = 0.3 ± 0.2).

3.2.2. Restorative Outcome Scale and Subjective Vitality Scale

Reliability—the internal consistency coefficients for both scales, respectively ROS and SVS, established on the basis of the data obtained was 0.889 and 0.862. The average values of these benefits (∆ROS, ∆SVS) with their expanded uncertainty intervals (with a confidence level of 95%) observed for each of the two tested types of exposure are presented in Figure 10.

Based on statistical analysis (t-test in Statistics), it was found that only one analyzed benefit (ΔROS) was statistically significant for contemplation of the forest. All other changes in ROS and SVS scores were not found to be statistically significant (

Table 4. Means, standard errors of the means and t-test results of psychological measures of ROS and SVS during the experiment.

Measures	Contemplation of the Forest			“Passive” Exposition			Total
	Mean (Std. Error)	t	p	Mean (Std. Error)	t	p	Mean (Std. Error)	t	p
ΔROS	0.59 ± 0.48 (0.24)	2.46	0.005 *	−0.01 ± 0.52 (0.26)	−0.03	0.97	0.29 ± 0.36 (0.18)	1.58	0.12
ΔSVS	0.41 ± 0.52 (0.26)	1.58	0.4	0.08 ± 0.5 (0.25)	0.32	0.75	0.24 ± 0.35 (0.175)	1.37	0.18

* statistically significant difference (p < 0.05).

).

3.2.3. Profile of Mood States

Reliability—the internal consistency coefficients for all subscales, established on the basic of the data were the following: ΔT = 0.889, ΔA = 0.889, ΔA = 0.839, ΔF = 0.801, ΔD = 814, ΔC = 680, and ΔV = 0.866. The average value of these benefits (ΔT, ΔA, ΔF, ΔD, ΔC, and ΔV) with the expanded uncertainty intervals (having a level of confidence of 95%) that were observed for each of two tested types of exposure are shown in Figure 11.

Based on the results of statistical analysis (t-test in Statistics) the increase in five (Tension, Anger, Fatigue, Depression and Confusion) of six mood dimensions were found for the significant results obtained in total for contemplation of the forest and “passive” exposure (

Table 5. Means, standard errors of the means and t-test results of psychological measures of POMS subscales during the experiment.

Measures	Contemplation of the Forest			“Passive” Exposition			Total
	Mean (Std. Error)	t	p	Mean (Std. Error)	t	p	Mean (Std. Error)	t	p
ΔT	0.47 ± 0.24 (0.12)	3.86	0.001 *	0.09 ± 0.22 (0.11)	0.85	0.407	0.28 ± 0.17 (0.085)	3.25	0.002 *
ΔA	0.32 ± 0.19 (0.095)	3.32	0.004 *	0.04 ± 0.14 (0.07)	0.55	0.593	0.18 ± 0.12 (0.06)	2.82	0.05 *
ΔF	0.21 ± 0.23 (0.115)	1.83	0.085	0.3 ± 0.3 (0.15)	2.04	0.056	0.25 ± 0.18 (0.09)	2.77	0.009 *
ΔD	0.15 ± 0.12 (0.06)	2.51	0.022 *	0.13 ± 0.11 (0.055)	2.31	0.033 *	0.14 ± 0.08 (0.04)	3.46	0.001 *
ΔC	0.27 ± 0.22 (0.11)	2.44	0.013 *	0.11 ± 0.31 (0.155)	0.74	0.471	0.19 ± 0.19 (0.095)	2.04	0.05 *
ΔV	0.02 ± 0.29 (0.145)	0.14	0.9	0.3 ± 0.21 (0.105)	2.85	0.011 *	0.16 ± 0.18 (0.09)	1.74	0.09

* statistically significant difference (p < 0.05).

). In the case of contemplation of the forest, four dimensions (Tension, Anger, Depression and Confusion) improved to a statistically significant degree. In contrast, in the case of “passive” exposure, only two improved (Depression and Vigor).

Based on the data in Table 5, the beneficial change in the total mood disturbance (ΔTMD = ΔT + ΔD + ΔA + ΔV + ΔF + ΔC) was calculated. The average values of this total index are shown in Figure 12. Statistically significant improvement in emotional state was observed for contemplation of the forest (ΔTMD = 1.5 ± 0.5), for “passive” exposure (ΔTMD = 1.0 ± 0.5) and for results obtained in total for contemplation of the forest and “passive” exposure (ΔTMD = 1.2 ± 0.4).

4. Discussion

4.1. Physiological Effects

Our research clearly shows that being in a forest environment had a positive effect on the mental relaxation of the respondents. A considerable volume of empirical research suggests that exposure to the natural environment has positive effects on physiological and cognitive functions, including reducing physiological stress [52] and restoring the ability to focus attention [53,54]. To date, there have already been many studies [32,48,55,56] focusing on the effects of physiological stress release from visits to natural areas (forests) and, by comparison, urban environments. Field experiments show that forest visits significantly increase parasympathetic nervous system activity and significantly suppress sympathetic activity in participants, compared to urban environments [56]. A reduction in heart rate was also frequently observed in previous studies on forest recreation [44,57]. Clearly, a short recreation program can be a useful tool in combating stress, as indicated by the study of Van der Zwan et al. [58]. A day trip to a forest park significantly increases the activity and number of natural killer (NK) cells and levels of intracellular anti-cancer proteins, reducing blood cortisol (stress hormone) and urinary adrenaline levels [59]. Stress reduction as a result of contact with nature can simply be the result of relaxation and a break from daily chores, but can also result from direct sensory stimulation from nature, such as exposure to smells [60] and sounds [61]. Experimental studies tend to show beneficial (short-term) effects by just looking at natural scenes, especially compared to urban scenes [62].

Our results show that only a form of stay in the woods that involves deliberate attentiveness and as full engagement of the senses as possible is guaranteed to effectively combat stress. We observed that blood pressure significantly increased as a result of activity combined with work with an academic textbook. The fact that people stayed in the forest did not help much in this regard. However, many previous studies [26,44,57,63] have confirmed that recreation in forested areas, even of short duration, contributes to a reduction in blood pressure. It seems that staying in the forest alone is not enough to lower stress levels as measured by indicators such as elevated blood pressure and heart rate. Only being in the forest combined with contemplation of the landscape, focusing attention on the surroundings, on the forest landscape, allows better recovery. Therefore, we observed a significant statistical reduction in heart rate in the group contemplating the forest landscape. This observation may be one of the pieces of evidences supporting the effectiveness of forest bathing and indicating its therapeutic importance.

4.2. Psychological Effects

The results of our study show that observing the forest landscape, and perception of it through the senses of sight, smell and hearing, clearly improves people’s well-being. We observed a significant increase in positive feelings as a result of activating the senses in the forest, while the decrease in negative feelings was not so significant. Many previous studies on forest recreation have indicated that an increase in positive feelings is accompanied by a decrease in negative feelings. Mostly, however, these were studies comparing two contrasting environments, city vs. forest [22,64]. The Mood State Questionnaire was a common measure of the effects of relaxation and stress management in forest environments. Park et al. [65] showed that walking in the forest and sitting and observing the forest landscape had attention-restoring effects. Previous studies have shown that viewing nature effectively reduces mental fatigue, irritability, anger and anxiety, maintains attention and interest, and increases concentration and feelings of pleasure [59,66]. In addition, a study by Tsunetsugu et al. [47] suggests that even short-term forest viewing has a relaxing effect.

In our study, we focused on comparing two variants of passive activities performed in the forest. From the time that the study took place inside the forest, we did not note any significant changes within the negative feelings.

In both exposure variants, the level of negative feelings was similar. The level of negative emotions in the forest was generally low, which was also confirmed in many previous studies [67]. We believe that the marked increase in positive feelings is the result of greater involvement of the optical perception of the forest. The forest landscape is the sum of many stimuli, not only auditory or olfactory, but, primarily, visual. Indeed, as estimated [55], on average, sight perceives about 87% of the stimuli coming from the landscape, with hearing perceiving 7%, smell 3%–5%, touch 1%–5%, and taste 1%. The main part of landscape perception occurs through the sense of sight and, therefore, visual impacts of land-use or management activities are important. Multisensory perception of the forest definitely has a positive effect on the human psyche, much more so than auditory and sound perception (reading a book in the forest excluded optical perception of the forest landscape).

Compared to the passive activity of reading a text, the ROS restoration rate for the activity of contemplating the forest landscape was statistically significantly higher. This is an interesting observation, because a lot of previous work [24,26,27,44,46] has suggested that recreation in forested areas, regardless of the type of activity, has restorative properties. Viewing the landscape was one of the forms of recreation analyzed in the study by Takayama et al. [52], Janeczko et al. [22], and Park et al. [65]. A study by Takayama et al. [40] indicated that viewing a forest landscape, similarly to walking combined with observation, clearly induced feelings of subjective restoration (ROS). Our study shows that this form of recreational activity, which engages the senses to a greater extent, particularly the sense of sight, has significantly greater restorative value.

Another benefit we analyzed as a result of recreation in the forest was the level of vitality. Vitality is a concept that can be estimated objectively through physiological responses or subjectively through psychological responses [53,54,56]. In the present study, subjective methods were used, as in the studies of Bielinis et al. [21] or Takayama et al. [18] and Janeczko et al. [22]. Studies conducted in forest environments have shown that recreation contributes to an increased sense of vitality [57,63]. Our earlier work [22] suggested that the level of vitality may be related to the type of physical activity and level of exercise. In the case of these studies, both forms of recreation analyzed were passive in nature, hence we probably did not observe statistically significant differences in the level of vitality stimulation as a result of their implementation.

Our study confirms that staying in the woods contributes to improved mood. The indices of four of the six POMS subscales (Tension–tension, Anger, Depression and Confusion–distress) were statistically significantly different, in favor of the activity of contemplation, visually observing the forest. Previous studies [58,60,61] confirm that the values of tension, depression, anger, confusion and fatigue indices decrease in the forest environment. A deciduous forest in the spring is particularly beautiful, with luscious greenery and lots of sounds of nature awakening to life, setting a positive mood. So it is not surprising that we observed a marked reduction in the above-mentioned scales. But this reduction was due to the fact that the study participants immersed themselves in the forest, contemplating the forest landscape. For the activity of reading a book in the forest, the benefits of being in the forest were not as comprehensive. Only two dimensions of the mood scale—Depression and Vigor—improved statistically significantly. It turns out, in the context of depression, that being in the forest, no matter what form it takes, passive or active, leads to health benefits and a decrease in depressive feelings. However, a greater decrease in depressive feelings is guaranteed by contemplation of the forest combined with visual perception. The fact that the recreational activity of reading a book in the forest also contributes to a decrease in depressive feelings is, in our opinion, an interesting finding, but, due to the small study sample, it requires further research. Depression is a growing health and social problem. Approximately 3.8% of the world’s human population suffers from depression [62,68,69]. According to a report by the World Health Organization [70], depression will be the most common disease in the world by 2030. Therefore, more scientific reports are needed to protect people and effectively fight this disease. In the case of the vigor scale, the observed increase in this feeling may have been due to the fact that the participants in the experiment were more motivated and focused on a specific activity—in this case, reading a book. They were motivated to do so by being prompted to answer several questions about the text they were reading. They read the book in a way that was not forced, but directed by the need of this experiment. Being motivated to do something naturally makes people more animated, with more enthusiasm and a sense of vitality.

5. Limitation

Our study has several limitations. One of them may be the fact that we based the study on a relatively small research sample. This was dictated by a number of considerations: it was an experimental study, with no specific source of funding. Participants were involved on a volunteer basis. Moreover, many other studies based on psychological testing relied on a comparable research sample size. For example, An et al. [61] included 13 students, while Takayama et al. [40] had 17 participants, and Bielinis et al. [71] study included 24 participants. The experiment was conducted with a group of young adult Poles. This may mean that our results may apply to this group only. On the other hand, our experiment had to be based on young people because an important part of it was the educational aspect. Participants read the text of an academic handbook and then had to answer in writing some questions about the same material. It is hard to imagine that older people would willingly want to participate in a similar study. At this point, another limitation arises. We cannot say how relevant the fact that we imposed a specific type of reading material on the participants is to the results obtained. Perhaps the pleasure derived from reading a favorite book, or any fiction novel, would guarantee greater emotional benefits. This thread definitely needs to be explored further. In future studies, we intend to test whether blocking visual gaze really reduces the health benefits of being in a forest environment so much. In addition, we conducted our research in only one season, spring, when, after the winter break, everything awakens to life and the emotional sensations of being among nature, in the forest, can be particularly intense. That is why we plan to conduct similar experiments in future seasons as well, in order to clearly determine whether just the fact of being in the forest contributes to one’s well-being, or whether a more conscious, fuller immersion in nature is necessary.

6. Conclusions

Mood and stress are particularly relevant when incomes to mental wellbeing (improvement in positive PANAS and statistically significant improvement in emotional state was observed for contemplation of the forest for both type of exposure). Being in the forest definitely increases people’s psychological well-being. However, the level of benefits enjoyed as a result of contact with nature depends on the degree of involvement and immersion in nature. With the fuller involvement of our senses in the process of perception of the forest, the regeneration process is more complete, and more effective (improvement in positive PANAS, improvement in the ROS index and increase in four mood dimensions—Tension, Anger, Depression and Confusion). In this sense, forest bathing is the best form of relaxation that can be obtained as a result of contact with the forest.