The body comprises an interconnected network of physiological systems fine-tuned throughout evolution to achieve and preserve a relatively stable internal state – homeostasis (Everly & Lating, 2019). Sometimes this equilibrium will be in a state of disharmony arising from intrinsic, extrinsic, real, or perceived forces, known as stressors, which the body needs to counter to maintain or reestablish the threatened homeostasis (Tsigos et al., 2016; Cool & Zappetti, 2019). The disharmony reflects the body’s inability to allocate sufficient resources to restore the balance, meaning that the body is in a stressed state. When the brain perceives stress, it activates coordinated neurophysiological responses in the brain and the periphery to initiate behavioral and physiological responses that facilitate allostasis (stability through change) and adaptation (Cool & Zappetti, 2019). It takes place through a process referred to as adaptive stress response, which enhances resilience and facilitates coping mechanisms to prevent future adverse impacts from stress stimuli (Suri Vaidya, 2015). However, there is a notable variation in individual response mechanisms to stress, perhaps due to people’s uniqueness, which is why it would be prudent to consider this aspect when recommending stress management strategies. Consequently, the current review explores the significance and feasibility of nature/plants as a stress-reduction strategy.
Role of Nature in Stress Management
Nature provides a range of services and benefits to the ecosystem, much of which past research has extensively covered. The least appreciated is perhaps the impact it has on psychological well-being and health through what Bratman et al. (2019) refer to as psychological ecosystem services. These services encompass a range of cognitive and psycho-physiological outcomes stemming from two mechanisms, considered to be the two primary environmental psychology theories (Jiang et al., 2020).
Attention Restoration Theory (ART)
The first is Kaplan & Kaplan’s (1989, as cited in Ohly et al., 2016; Jiang et al., 2020) Attention Restoration Theory (ART). The basic premise underlying the theory is that natural environments contain elements that provide a relaxing space through which humans can relax and reduce mental fatigue, which helps restore voluntary/direct attention. Direct or voluntary attention refers to the human ability that allows people to pay attention to a particular task requiring effort (Ohly et al., 2016). However, this ability is finite and becomes exhausted with use, especially if overworked or overloaded with mental processes. For example, focusing requires the individual to exclude other thought stimuli from nearby environments. Voluntary attention makes this possible by suppressing distractions that may be inherently more interesting. Nonetheless, fatigue may set in when there is no motivational draw to rest or restore the ability. Attention fatigue leads to poor decision-making and self-control, potentially threatening individuals’ health through neural and behavioral pathways to cause conditions like obesity (Ohly et al., 2016). ART proposes that individuals experience nature as it offers a relaxing and refreshing environment that facilitates and enhances their ability to reflect and consider any unresolved issues. According to Jiang et al. (2020), the “softly fascinating” aspect associated with natural elements like trees, water, and sunsets helps capture an involuntary attention sphere in humans, which provides a means through which rest and recovery can take place. The reason is that the inherent characteristics associated with these elements that draw human interest require minimal mental effort to process, thus causing no strain on the voluntary human attention paid to them.
Stress Reduction Theory (SRT)
The second is Ulrich’s (1991, as cited in Jiang et al., 2020) Stress Reduction Theory (SRT). The primary argument is that the natural environment presents an unthreatening setting that provides humans with the space to calm down, generate positive feelings, and reduce arousal. Ultimately, natural environments will promote stress recovery by reducing the adverse psychological and physiological signs of stress (Jiang et al., 2020). According to Ulrich et al. (1991), humans may not have the same capacity to recover from stress in artificial settings as natural ones because human evolution mostly occurs within the latter context. Essentially, the argument Ulrich drives with SRT is that the natural environment can improve individuals’ positive affect and attention following a stressful event. It can operate as a remedy or solution in stress management as the natural environment possesses certain qualities that provide the individual with an incentive to adapt due to the positive affective appraisals derived from them (Ratcliffe et al., 2013). These qualities can either be aesthetic or semantic. Aesthetic elements may feature as perceived complexity, patterns, texture, or environmental mystery, while semantic elements through such aspects as absent threats or resource availability. Whichever the case, human beings can make use of natural spaces to reduce stress because these inherent characteristics reduce blood pressure, lowers cortisol levels in the body, self-reported stress, and increases positive mood (Jiang et al., 2014; Ewert & Chang, 2018). The SRT and ART environmental psychology theories support the idea that nature facilitates restoration from mental fatigue, stress, and negative moods, thus improving individuals’ health and well-being.
Several past authors have conducted tests and analyses to determine the relationship between nature and stress management, focusing on consequent impacts like performance, attention, health, and well-being. For example, Dravigne et al. (2008) sought to investigate whether having indoor plants in the office and having windows overlooking green landscapes could influence employees’ job satisfaction levels. The underlying motivation was that recreating a natural environment in the office or exposure to one could reduce employees’ stress levels by creating a calming and comfortable working environment to foster job satisfaction. The study results showed that employees perceive work environments exposed to nature as more comfortable, consequently influencing their job satisfaction and quality-of-life scores. A more recent study by Toyoda et al. (2019) corroborates the finding that plant or nature-oriented work environments enhance employee well-being by reducing office workers’ psychological and physiological stress. The author identified three levels of involvement that can help with promoting mental health in the workplace. These include passive observance, the prescribed activity of staring at the plant, and active involvement in selecting and caring for the office plant (Toyoda et al., 2019). These observations within a work setting context align with the SRT and ART functional mechanisms of stress management.
Nonetheless, the findings are not always consistent, as some authors find a very minimal association between nature exposure and improved performance and mental well-being. Bringslimark et al. (2007) carried out a study to explore the potential benefits of placing indoor plants in a work setting. The findings indicated a minimal association between nature exposure and proxies for employee well-being like self-reported stress, sick leaves, and productivity. These may infer that nature may not significantly impact mental health and well-being, as indicated in the SRT and ART theories. Authors like Korpela et al. (2017) and Lottrup et al. (2012) corroborate the outcomes by finding limited support for the link between employee well-being over time and nature exposure in a work setting. These investigations show that nature exposure studies can only explain a small portion of stress reduction variance within work settings. These studies may have differing opinions on the significance of nature/plant exposure in work settings to improve employee well-being and productivity. However, it is important to acknowledge that they do not return negative associations, meaning that nature exposure does have relevance in psychological and physiological balance. Furthermore, most people spend much time at work over their lifespans, inferring that these small associations could culminate in an overall significant impact in the long term.
It would be plausible that the pattern is limited to the work and office setting context, so exploring other stress settings would be appropriate to elucidate the outcome in other stress-associated settings. However, partial positive findings are consistent with the meta-analytic review conducted by McMahan and Estes (2015). An excellent example is school and learning institution contexts. Here, class and learning settings, including high expectations for success, schoolwork, low performance, fear of failure, and conflict, impose pressure on students, possibly leading to stress (Deb et al., 2015; Hirvonen et al., 2019). In one study, Daly et al. (2010) investigated the impact that indoor plants would have on student reading, spelling, and analytical outcomes. The results reported a 10-14% improvement, which categorizes as significant progress by educationists. The results also exhibited a lack of change in one of the schools. However, it could be perhaps due to the active gardening program involving ornamental and vegetable species, meaning that students were already exposed to nature and had a continuing relationship with it compared to those introduced to nature during the investigation.
Further studies have explored various other attributes related to the learning institution environment, focusing on performance, creativity, health, and well-being. The study by Studente et al. (2016) examined various attributes associated with nature, such as the use of live plants, nature views, and the color green and their impact on visual and verbal creativity. The results found that exposure to nature enhanced visual creativity among students and no impact on verbal creativity. There are three critical implications to these findings. The first is that it proves exposure to nature or green landscapes can improve creativity, which is a core tenet of performance as part of the critical thinking ability that enhances achievement (Gajda et al., 2017). The second inference is that creativity is domain-specific, meaning that practitioners must take caution in the approach used to mitigate stress. Some stress management methods may not have any impact if directed to the wrong domain (Studente et al., 2016). Nonetheless, the research does acknowledge that nature exposure has a positive impact on creativity but can also extrapolate to infer positive outcomes on well-being – the third implication. The assertion stems from Schutte et al.’s (2017) revelation that there is a significant relationship between visual stimulation or exposure to green landscapes and students’ positive affect and well-being. These observations
Aside from the work and educational contexts, using nature in stress management has also received attention for its use in general contexts. Given the progression of contemporary living and conditions, there is a need to evaluate the consequence of nature exposure and interior plants’ use in practice. The positive outcomes within learning institutions reflect those observed within the work context. Earlier studies like Lohr et al.’s (1996) observed a general impact of using interior plants on productivity. The research proved that plants and nature could resolve attention deficits and foster greater reaction times to tasks requiring some visual concentration. They can do so because the visual stimulation of plants possesses physiological and psychological relaxing effects, as observed in Ikei et al. (2014). The study recommended using foliage plants to help shift the sympathetic/parasympathetic balance to improve mood as a simple method strategy for reducing stress and improving mental health for high school students.
Park & Mattson (2009) at a similar conclusion but within hospital settings, noting the therapeutic value possessed by plants in hospital environments. Plants provide a non-invasive, affordable, and effective complementary medicine for surgical patients. The authors recommended their use to medical practitioners to enhance the healing environment for their patients. Lee et al. (2015) explain how this therapeutic mechanism operates in their study The therapeutic mechanism through which this occurs. The authors found that using interior plants in places requiring significant mental effort can reduce mental strain. Plants suppress the sympathetic nervous system activity and diastolic blood pressure, thereby promoting comfortable, soothing, and natural feelings that enhance one’s self-control. In so doing, individuals can more realistically and practically engage tasks with optimal outcomes.
In conclusion, there appears to be a bulk of literature that supports the idea that exposure to nature, green landscapes, or the use of interior plants in different settings induce positive feelings and mood, reducing or preventing instances of stress among individuals. The available literature has not yet identified any observation suggesting a negative relationship as yet. However, more empirical research should help provide a more comprehensive and detailed understanding of the potential benefits natural environments provide when dealing with stress. Nonetheless, the current literature supports its use as a stress management approach, even with minimal improvements as there is no notable shortcoming or loss from its application.
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