Nature’s therapeutic power: study on the psychophysiological effects of touching grass

Study reveals that touching real grass increased relaxation, comfort, a sense of naturalness and decreases anxiety levels.

Photo by Ochir-Erdene Oyunmedeg on Unsplash

High rates of urbanisation and the extensive use of electronics is increasingly disconnecting people from nature and thereby putting the health of urban residents at risk. Over 50% of the world’s population currently live in cities, and this number is increasing. In 1950, urban inhabitants composed 30% of the world population which increased to 54% in 2014. Projections indicate that cities will host 66% of the world population by 2050.

Scientists know of the contrasting levels of urban and rural amygdala stress. The amygdala is an area of the brain that contributes to emotional processing and interprets images and sounds. When it perceives danger, it instantly sends a distress signal to the (hypothalamus) brain to activate a fight-or-flight response. When the threat passes, the (parasympathetic) nervous system puts on the brakes and dampens the stress response. However, many people are unable to find a way to put the brakes on stress and experience (chronic) stress, contributing to the health problems. Urbanites reportedly exhibit greater amygdala activation than ruralites, experiencing higher levels of stress due to (noise, light) pollution, violence and social isolation as opposed to the greener settings experienced by rural populations which is known to reduce the stress.

This study, conducted amongst female Chinese university students, aimed to investigate the physical and psychological benefits of spending time in nature. The benefits of touching real grass and artificial turf (the control activity) outdoors with the palm of the hand for five minutes were measured. Blood pressure and electroencephalography (EEG) as well as State-trait Anxiety Inventory (STAI) scores, and the semantic differential scale (SDM) were used to investigate psychophysiological responses.

The results of study showed that touching real grass was associated with significant changes in brainwave rhythms and a reduction in both systolic and diastolic blood pressure compared to touching artificial turf. Thereby indicating that contact with real grass may reduce physiological and psychological stress in adults. In addition, SDM scores revealed that touching real grass increased relaxation, comfort, and a sense of naturalness while decreasing anxiety levels.

Many studies have shown that horticultural activities not only improves physical functions and muscle activation, but can also reduce depression and anxiety, boost self-esteem, and boost cognitive function (Brain-derived neurotrophic factor (BDNF)). The findings of this research indicate that the simple act of touching grass is potentially a method for establishing a connection with the natural environment.

Perhaps also a cue to look after our grass verges, rather than parking our cars on it.