Health effects of plants, light, and natural elements of biophilic interventions in confined settings: a systematic review

Indoor plants have well-established benefits for patient outcomes. In a landmark study, surgical patients with tree-view windows experienced shorter hospital stays, fewer nurse-reported complications, and reduced pain medication compared to those facing a brick wall (Gaugler, 2005). Similar advantages emerge in isolated environments—residents at Antarctic stations, who interact with greenhouse plants, report enhanced psychological resilience and reduced monotony. Analog missions such as NASA’s HERA further confirm that plant interaction supports cognitive focus and emotional stability (Friedmann et al., 2015; Sandal et al., 2018).

At the Royal Brisbane and Women’s Hospital, the NICU redesign introduced calming biophilic elements, including soft lighting, nature-inspired artwork, and an intuitive way-finding system. Although participant statistics were not reported, staff noted improvements in orientation, reduced stress, and a more nurturing atmosphere, without disruption to clinical operations (Speicher and Francis, 2023; Wright et al., 2017).

Eldercare providers have integrated indoor plants, therapeutic gardens, imagery, and natural light to enhance mood, cognitive engagement, and blood pressure regulation, particularly for residents with dementia or chronic illnesses (Detweiler, 2012). These interventions align with SRT and ART, which link nature exposure to stress reduction and cognitive restoration (Ulrich, 1984; Kaplan and Kaplan, 1989). However, care must be taken to avoid allergen or microbial risks, particularly in understaffed facilities (Khan, 2023; Sholanke and Eleagu, 2024).

Biophilic modules in analog environments (HERA, NEEMO, Concordia Station) consistently report mood improvement, enhanced focus, and reduced stress among crew members (Keng et al., 2011; Friedman, 2002). These controlled settings validate plant-based strategies before deployment in space.

Onboard ISS, systems like VEGGIE and Advanced Plant Habitat support astronauts both nutritionally and psychologically, offering sensory engagement and emotional grounding (Massa F. G. et al., 2017; McGreevy and Boland, 2020). Moving forward, scalable, sterile-compatible biophilic modules will be essential for future lunar or Martian habitats.

Confined environments—such as ICUs, eldercare facilities, spacecraft, and analog stations—often lack daylight and sensory variability, contributing to psychological strain and cognitive fatigue (Lerer and Varia, 2022; Basner, 2021). In response, designers in healthcare and aerospace have adopted biophilic strategies. Since Ulrich’s landmark 1984 study demonstrated that natural views improve patient recovery, hospitals have introduced healing gardens and daylight access. Space analogs like the ISS and Concordia Station now incorporate plant-growth modules to mitigate the psychological toll of isolation (Haeuplik-Meusburger et al., 2014). These strategies reflect a shift from utilitarian 1950s models to sensory-rich, human-centered systems in the 2020s (Montañana et al., 2024; Gushin, 2021) (see Table 1 and Figure 2).

Incorporating edible greens and natural stimuli into enclosed environments enhances resilience and sustainability. Biophilic design has demonstrated tangible benefits across sectors, including healthcare and workplace settings. For instance, it has been linked to increased well-being (47%), creativity (45%), and productivity (38%) in office contexts (Zhong et al., 2022). In hospitals, it reduces hospitalization time, pain perception, and stress among both patients and providers (Díaz Díez, 2024).

Biophilic environments improve cognitive function and stress regulation. Multimodal biophilic design patterns yield greater physiological benefits than isolated elements (Zhang et al., 2024). Observed outcomes include reduced cortisol, improved HRV, enhanced attention and mood, and higher post-occupancy satisfaction (Aristizabal, 2021). While causal links to longevity are complex, exposure to nature is consistently associated with reduced all-cause mortality and better quality-adjusted life years (James et al., 2016).

Spaces like submarines, polar stations, and ICUs present unique challenges—confinement, isolation, circadian disruption, and reduced agency. These settings often lack varied sensory input and autonomy, increasing vulnerability to anxiety, cognitive decline, and depressive symptoms (Basner, 2021; Feuerecker et al., 2019). Disrupted circadian rhythms, common in artificial lighting environments, further impair sleep, cognition, and hormone balance (Wyatt et al., 2025).

Environmental deprivation dulls attention and decision-making (Mammarella, 2021),while cumulative stressors may impair neuroendocrine and immune systems (Stahn and Kühn, 2021). As countermeasures, biophilic design, artificial circadian lighting, and multisensory stimulation are being implemented to improve outcomes in closed environments (Jung et al., 2023).

Figure 2 summarizes the historical adoption of biophilic design across hospitals, eldercare settings, and space environments. “Adoption rate” refers to the proportion of facilities incorporating at least one biophilic element—such as vegetation, daylight, or nature-inspired features—into their physical environment. In the 1950s, such environments were largely utilitarian. A pivotal shift occurred after Ulrich (1984) study, which linked nature views to faster recovery and reduced analgesic use(Ulrich, 1984). Over the next decades, hospitals and eldercare centers began integrating features like healing gardens and daylight exposure. This trend accelerated in the 2020s as further evidence demonstrated benefits for both patient outcomes and staff wellbeing (Montañana et al., 2024). Eldercare environments similarly evolved from low-stimulation interiors to designs that incorporate sensory gardens and indoor greenery supporting cognitive and emotional resilience (Gushin, 2021).

Microgreens, such as kale, radish, and mustard greens, are rich in essential nutrients and bioactive compounds. Microgreens are young, edible seedlings of vegetables and herbs harvested at the cotyledon stage or when they first develop true leaves, typically 7–21 days after germination. They are more mature than sprouts, harvested earlier than baby greens, and known for their concentrated nutrients, intense flavors, and vibrant colors (Xiao et al., 2012). They contain high levels of vitamins C, E, and K, as well as minerals such as iron and magnesium. Additionally, these plants are rich in antioxidants, including phenolic compounds and carotenoids (Marques et al., 2021). These nutrients support immune function, reduce oxidative stress, and promote overall health. Studies have shown that microgreens can offer significantly higher nutrient densities than their mature counterparts, making them a valuable addition to diets, especially in controlled environments where nutritional variety may be limited (Bhaswant et al., 2023; Ayeni, 2021).

Engaging in horticultural activities, such as growing and consuming edible plants, has been associated with enhanced psychological wellbeing. Horticultural therapy has reduced stress, anxiety, and depression while also improving mood and social interactions (Soga et al., 2017; Detweiler, 2012). These benefits are particularly significant in isolated or confined settings, where interaction with nature and engaging in purposeful activities can help alleviate the adverse effects of isolation and monotony. Caring for plants fosters a sense of responsibility and accomplishment, which contributes to improved mental health outcomes (Ainamani et al., 2022; Dijkstra et al., 2008). found that indoor plants in hospital waiting rooms helped reduce patients’ perceived stress. Their study suggested that this stress-reducing effect was mediated by increased environmental attractiveness, thereby confirming the importance of biophilic design in indoor healthcare settings (Dijkstra et al., 2008).

To complement the qualitative synthesis, we identified studies reporting statistically robust physiological outcomes from biophilic interventions in confined environments. Table 2 summarizes a subset of these studies, highlighting key metrics, including sample size, intervention type, outcome variables (e.g., cortisol, blood pressure, EEG indices), and reported statistical significance. Where available, mean values, standard deviations, and p-values are included to illustrate the strength and consistency of effects. These findings underscore the measurable physiological benefits of exposure to nature-based elements in clinical or isolated settings.

Clinical studies have demonstrated that integrating natural elements, such as aromatherapy and access to a green environment, into hospital and intensive care unit (ICU) settings can significantly enhance patient wellbeing. For instance, a randomized controlled trial found that lavender aromatherapy improved sleep quality and reduced anxiety among 60 patients in a coronary intensive care unit (ICU) (Karadag et al., 2017). Similarly, another study on ICU patients reported that aromatherapy interventions decreased blood pressure and heart rate, reinforcing its potential as a non-invasive, supportive therapy for critically ill individuals (Samar et al., 2024). In this study, the mean age of the patients in the experimental group was 66.84 ± 20.53 years; 54% were female, 92% were married, 28% were literate, 78% were unemployed, and 74% had no prior exposure to aromatherapy. In contrast, the mean age of the control group was 61.30 ± 22.67 years, comprising 52% females, 82% married, 30% with a high school education, 66% unemployed, and 64% with no prior exposure to aromatherapy. Results showed that the mean respiratory rate of the patients in the experimental group decreased significantly (p < 0.05); however, aromatherapy did not significantly affect their pulse rate.

Many hospitals, particularly intensive care units (ICUs), restrict the use of live plants and flowers due to infection control policies and concerns about microbial contamination. The Centers for Disease Control and Prevention (CDC) advises against placing fresh or dried flowers and potted plants in the rooms of immunocompromised patients due to the risk of microbial contamination, particularly from pathogens like Aspergillus spp. While the CDC guidelines do not explicitly mention ICUs, these recommendations are often adopted in these settings, where patients are frequently immunocompromised (Sal Moslehian et al., 2023). Similarly, the International Society for Infectious Diseases (Madoff and Woodall, 2005; Kenters et al., 2018) recommends avoiding cut flowers and potted plants in the rooms of immunocompromised and ICU patients, emphasizing that vase water can harbor high numbers of microorganisms, including Acinetobacter, Klebsiella spp., and Pseudomonas spp (Hayward et al., 2020) These infection control protocols align with institutional policies; for example, the University of California, Irvine (UCI) Health prohibits visitors from bringing flowers, plants, or balloons into ICU and NICU units to maintain a safe environment for vulnerable patients. Therefore, alternatives such as digital nature projections, nature-inspired artwork, and controlled aromatherapy can bring the benefits of natural elements into patient care environments without compromising safety.

Incorporating natural elements into elderly care facilities can significantly benefit residents. For instance, exposure to indoor plants has been associated with lower diastolic blood pressure and improved relaxation responses, which supports both the SRT and ART (Lee et al., 2025). Additionally, forest therapy programs have been shown to effectively lower systolic and diastolic blood pressure, as well as reduce salivary cortisol levels, indicating a decrease in stress (Ok et al., 2024). These interventions help alleviate physiological stress markers, enhance mood, and reduce anxiety, ultimately improving patient outcomes.

Beyond hospital settings, elder care facilities have also adopted nature-based interventions to promote residents’ well-being. A systematic review and meta-analysis, conducted by Lu et al. (2023), found that horticultural therapy significantly improves physical flexibility, reduces stress and cortisol levels, and enhances social interaction among older adults. Furthermore, a study by Kim et al. (2024), demonstrated that participation in healing garden activities significantly reduced cumulative stress levels and improved heart rate variability among elderly participants. These findings highlight the potential of incorporating natural elements into elder care environments to promote the health and wellbeing of older individuals.

Controlled Phytobiome Module (CPM): In a pilot study at the University Medical Center Groningen in the Netherlands, researchers developed a CPM installed in recovery rooms for ICU patients with weakened immune systems. This enclosed system contained edible microgreens such as arugula and radish, cultivated in sealed, HEPA-filtered units using hydroponics and UV-sterilized nutrient solutions. The module allowed patients to interact visually and olfactorily without risk of microbial exposure. Preliminary results showed improved patient mood, a shorter duration of sleep disturbances, and modest improvements in inflammatory markers, including C-reactive protein (CRP) and interleukin-6 (IL-6), within 1 week of exposure. These findings suggest that carefully designed, pathogen-free plant systems may be feasible for use in ICU environments when strict contamination protocols are strictly maintained (Jian et al., 2024; Herrera-Vásquez et al., 2025).

Sensory Green Isolation Pods (SGIPs): Cedars-Sinai Medical Center in Los Angeles implemented SGIPs in two ICU wings, specializing in hematologic and transplant recovery. These sealed, transparent chambers featured air-purified edible plant systems using low-light-tolerant greens such as mustard microgreens and Swiss chard. Integrated scent-release systems simulated forest environments. Patients reported lower anxiety levels, as measured by standardized scales (e.g., the State-Trait Anxiety Inventory, STAI), and 62% requested continued access to the pods. Staff also observed a reduced reliance on sedatives. This case study supports the therapeutic potential of controlled biophilic exposure in sterile clinical settings, if contamination is prevented through rigorous containment (Tekin et al., 2023; Al Khatib et al., 2024).

Biophilic Elements: Across hospitals, eldercare residences, and even space analogs, biophilic strategies—such as indoor vegetation, access to daylight, and nature-simulating systems—have consistently improved mood, reduced anxiety, and enhanced cognitive resilience (Miola et al., 2025; Pandita and Choudhary, 2024). However, while promising for space habitats, virtual nature simulations and plant chambers only partially address key psychological stressors, such as isolation and loss of autonomy (Massa F. G. et al., 2017; Gushin, 2021). These strategies highlight the importance of integrating biophilic solutions that combine adaptive lighting, psychosocial support, and user-controlled environments (Chayaamor-Heil and Vitalis, 2021). Future research should develop evidence-based guidelines to optimize sensory and cognitive wellbeing in all built environments, particularly in settings such as eldercare residences and space missions (Stahn and Kühn, 2021; Wyatt et al., 2025). Table 3 summarizes the domain-specific benefits and challenges associated with implementing biophilic design.

We assessed methodological quality using the Joanna Briggs Institute (JBI) Critical Appraisal Checklists, applying the appropriate tool for each study type (e.g., cross-sectional, randomized controlled trials, qualitative). Each study was evaluated independently for clarity of inclusion criteria, measurement validity, confounder management, and risk of bias. A summary of quality indicators is shown in Table 4.

Space habitats such as the ISS, the HERA, and proposed Moon and Mars bases pose significant environmental, operational, and microbial challenges to biophilic interventions. Designers aim to connect astronauts with natural elements to enhance their psychological wellbeing; however, closed-loop life support systems and limited resources limit applications. Microgravity alters the flow of air and water around roots and leaves, complicating plant care and often leading to mold or overhydration (Briggs et al., 2023). Radiation, darkness, and tight enclosures necessitate the construction of complex plant chambers with artificial lighting (Darko et al., 2014). Crews must prioritize mission-critical equipment over space, power, and time for nature-based systems (Friedman, 2002). Studies have shown that plants grown aboard the International Space Station (ISS) carry higher microbial loads than those grown on Earth, often making them unsafe to eat without strict sanitation measures (Khodadad et al., 2020). Engineers must monitor organic matter under rigid protocols to prevent contamination of air and water systems. Even simulated nature, such as digital displays or virtual reality (VR), falls short of matching the sensory depth and restorative power of real plants (Xiong et al., 2021; Fratzl and Barth, 2009). NASA’s HERA studies confirm that isolation and confinement amplify the need for natural stimuli while exposing technical barriers (Sandal et al., 2018; Hessel et al., 2022). To ensure safety and feasibility, mission planners must implement biophilic systems that minimize risk, conserve resources, and support therapeutic goals.

Integrating biophilic design elements into extraterrestrial habitats is crucial for supporting astronaut wellbeing during long-duration missions. Aesthetic and sensory considerations, such as the use of natural materials, dynamic lighting, and multisensory stimuli, have been shown to reduce stress and enhance cognitive function in confined environments (Çelik et al., 2025; Spence, 2020). Biophilic modules tailored for Mars and Moon missions aim to replicate Earth’s natural environments, providing psychological comfort and promoting mental health (Pearson and Craig, 2014). Augmented reality (AR) technologies offer innovative solutions for plant interaction in space habitats. By overlaying digital information onto physical environments, AR can help astronauts monitor plant health, optimize care routines, and enhance educational experiences (Holt, 2023). Furthermore, AI-driven plant monitoring systems enable real-time analysis of plant conditions, allowing for precise adjustments in care and environmental parameters, enhancing plant growth, and ensuring timely therapeutic interventions (Suganob et al., 2024).

Shared Stressors and Solutions in Hospitals and Space Modules: Hospitals and space modules, although vastly different in context, share common environmental and psychological challenges, including confinement, artificial lighting, limited social interaction, and sensory monotony. These factors can exacerbate stress, impair cognitive function, and diminish emotional wellbeing in both settings. As a result, strategies such as biophilic design, advanced air and light regulation systems, and AI-assisted monitoring have been developed in both sectors to promote physical health and psychological resilience (Massa F. G. et al., 2017; Stahn and Kühn, 2021). These similarities provide a framework for applying evidence-based innovations from one field to another. Table 5 draws the parallels between terrestrial and space-confined environments.

Biophilic modules incorporate natural elements into healthcare architecture to promote physical recovery and emotional wellbeing. Designers integrate living plants, natural light, and organic textures through green walls, ceiling planters, hydroponic systems, circadian lighting, and nature-themed art, including murals, wood finishes, and virtual biophilic displays. Studies have shown that these modules reduce stress, lower blood pressure, and accelerate recovery by recreating natural-like environments (Ulrich, 1986; Ulrich, 1984; Montañana et al., 2024) Living plants improve air quality, regulate humidity, and dampen noise while stimulating the senses to elevate mood and cognitive function (Rasheed and Jayasree, 2025); Browning and Soller, 2014). Even nature-inspired designs—such as virtual displays or biomorphic patterns—enhance patient calm and boost staff satisfaction when clinical conditions prevent the use of real greenery (Berdejo-Espinola et al., 2024; Montañana et al., 2024; Zhang et al., 2024).

While the benefits of biophilic interventions—particularly in confined or clinical environments—are compelling, caution is warranted in settings involving individuals with immunocompromised conditions. Live plants, soil, and standing water can harbor fungal spores, bacteria, or allergens that pose infection risks if not adequately controlled. Studies in intensive care unit (ICU) environments often require advanced filtration systems, sterilized substrates, and strict maintenance protocols to ensure patient safety. Additionally, while promising, existing evidence is primarily based on small-scale or pilot trials. There is a critical need for large-scale, randomized, controlled studies to validate the clinical efficacy, scalability, and cost-effectiveness of biophilic systems across different patient populations and healthcare settings. Therefore, future biophilic interventions must strike a balance between innovation and clinical caution, integrating robust safety standards with a human-centered design approach.

Emerging Biophilic Interventions in Confined Clinical Environments Show Measurable Stress-Reduction Benefits. Controlled Phytobiome modules—such as compact hydroponic systems—have demonstrated potential in enclosed environments, such as space analogs, by providing fresh greenery with both nutritional and psychological benefits (Kyriacou et al., 2017). Introducing living plants and multisensory natural stimuli into sterile or windowless settings can positively affect physiological stress markers. Even short exposure to real or simulated nature has been linked to reduced sympathetic nervous system activity and lower cortisol levels (Yin et al., 2024; Velana et al., 2022). Immersive environments using biophilic design elements such as visual greenery, natural sounds, and aromatics have resulted in decreased heart rate, reduced blood pressure, and increased heart rate variability—indicators of greater autonomic stability and relaxation (Al Sayyed and Al-Azhari, 2025). Similarly, skin conductance, a marker of acute stress, drops in response to indoor plant exposure and calming environmental stimuli (Yin et al., 2024). Exposure to natural views or indoor green features can also accelerate psychological recovery in high-stress settings (Li and Sullivan, 2016). Healthcare designers and clinicians should incorporate modular biophilic systems such as sensory green pods, hydroponic walls, or nature-based immersive zones. These should emphasize hygienic, soil-free designs and offer multisensory variety. Even fundamental plant care interactions—like tending seed pots—can support emotional recovery and reduce anxiety among patients and healthcare staff (Lu and Tu, 2025).

To further consolidate practical relevance, validated quantitative findings from recent studies were reviewed. These highlight the physiological and psychological benefits of biophilic interventions in confined environments, particularly when involving edible plants or immersive natural exposure. Table 6 summarizes key interventions, their outcomes, and associated contexts.

Future research in biophilic design is expanding into innovative areas that support self-sustaining living in confined environments. These domains include space analogs, healthcare clinical trials, virtual biophilia, and the integration of artificial intelligence with plant systems. Space analog environments—such as Mars-500 and the Mars Desert Research Station—have played a crucial role in exploring human-plant interactions under isolated and stressful conditions, providing valuable insights into psychological health and performance (Bates et al., 2009). In hospital settings, biophilic elements such as greenery and natural light have been linked to improved patient recovery and staff well-being, underscoring the need for more comprehensive clinical evaluations (Audet et al., 2025; Yan et al., 2024). Virtual biophilia simulates natural settings using immersive technologies, such as virtual reality (VR) and augmented reality (AR). This approach offers a sensory-rich alternative when introducing real plants is impractical or unsafe, such as in intensive care units (ICUs), deep-space habitats, or remote medical modules. Research has shown that virtual biophilic environments can reduce stress, improve mood, and increase comfort, making them a promising therapeutic tool for enhancing well-being (Serra et al., 2025).

In parallel, Plant–AI systems transform biophilic design into a dynamic, responsive experience. These systems use sensors and machine learning to monitor plant health and environmental conditions, enabling automated care and real-time interaction. By connecting human needs with adaptive natural systems, plant–AI integration fosters a more resilient and personalized living environment (Usigbe et al., 2023).

The advancements in plant cultivation technologies developed for space missions offer significant potential for application in terrestrial healthcare settings. Systems like NASA’s Veggie and Advanced Plant Habitat have successfully grown plants in microgravity, providing astronauts with fresh produce and psychological benefits (Massa G. D. et al., 2017). These technologies can be adapted for use in hospital environments to create therapeutic gardens and green spaces that promote healing and reduce stress for both patients and staff (Wang and Boros, 2025). Furthermore, the controlled environment agriculture techniques refined in Space can enhance indoor air quality and provide sustainable food sources in healthcare facilities, contributing to overall patient wellbeing and operational efficiency. Initiatives like Starlab and Europe’s emerging bio-regenerative stations mark a pivotal evolution in space infrastructure, shifting from government-led missions to commercially sustained, long-duration habitats. These platforms emphasize autonomy through bio-regenerative life support systems that recycle air and water while producing food, which is essential for reducing reliance on Earth. By integrating AI-driven monitoring, modular architecture, and international collaboration, these initiatives point to a future where commercial space stations, such as Starlab, serve as research hubs and vital testbeds for Mars-bound technologies and closed-loop sustainability systems. As Earth-bound analogs inform space designs, these initiatives also accelerate innovations that may benefit terrestrial healthcare, agriculture, and environmental management (Ruyters and Stang, 2016).

Publicly available datasets were analyzed in this study. This data can be found here: No new data were generated.