I am relatively new to environmental therapeutics and wanted to consider the boundaries of our discipline. It is defined on the home page of cet.org as “harnessing the neglected properties of light, dark, and air to meet the challenges of mental and physical health in contemporary life.” Since 1994, CET has championed interventions such as bright light therapy, especially for various mood and circadian rhythm disorders. This made me think about what other properties of the environment could be harnessed to improve health. How far can we push the boundaries? Up until now, CET has defined the boundaries by the treatments that have the strongest evidence from randomized controlled trials (RCTs), for example: light, darkness and negatively charged air ions. However, there is no reason why other properties of the environment would not also show therapeutic action. I believe that there are some candidates (described below) which could be investigated and eventually recognized as an environmental therapy.  

Environmental interventions require varying degrees of behavioral interaction and effort by the individual to benefit. For example, bright light therapy requires some initiative, in that a person must switch on the light at an agreed time in the morning, sit usually about a foot away, and use it daily. Triple chronotherapy for the rapid treatment of depression requires further behavioral engagement by staying awake for 36 hours, followed by 4 days of delaying the time of sleep, together with ongoing daily morning bright light therapy [1,2].

We can think of other potential environmental interventions that could broaden the current definition. Interactions with nature come first to mind, such as “forest bathing” (shinrin yoku) or more complex activities such as gardening. There is already some evidence of benefit from RCTs [3,4], but we need to see more robust investigations in clinical populations with credible control groups, for example: walking in a forest versus walking in a city; gardening in a natural environment versus a hobby in a city environment. Little is known about moderators, such as how often or for how long these activities would need to be done to show and maintain therapeutic benefit.

Of course, an activity such as gardening is a multimodal event that encompasses exercise, daylight exposure, higher negative ion concentration than indoors, olfactory stimulation, not to mention aesthetic experience. Gardening certainly cannot be described by a single dosing dimension along which the benefit would vary.

Another intervention worth investigating, with simpler dimensional properties, is exposure to a low temperature, for example: cold showers, ice baths, and open water swimming. Cryotherapy (or cold-water therapy) is an anti-inflammatory that also enhances endorphin release. Theoretically, it could be considered for depression.  Currently, there is minimal, but positive, evidence from case series and from cold-water enthusiasts [5]. However, once we had a grasp on standardized protocols for treatment administration, we might find efficacy for various mental and physical health conditions.

These are just a few examples of environmental interventions that have been embraced by the public, but which academia has not yet investigated in terms of clinical and cost effectiveness, nor how to maximize effect.  More studies are required, so that perhaps one day CET will be able to broaden its definition of environmental therapeutics and expand the armamentarium of nonpharmaceutical adjuncts and alternatives.

David Veale Consultant Psychiatrist, South London, and Maudsley NHS Foundation Trust and Visiting Professor in Cognitive Behavioural Psychotherapies, Kings College London.