Until September BBC Gardeners’ World magazine is running a monthly feature ‘Grow Yourself Healthy’. The May issue focuses on how gardens and gardening can improve sleep, and featured Julie Darbyshire, researcher for the University of Oxford Critical Care Research Group (Nuffield Department of Clinical Neurosciences), alongside other sleep researchers and experts, discussing the benefits of gardening ahead of the RHS flagship flower show in Chelsea.
If you’re not tired, you’re not going to fall asleep. It is perhaps obvious when you think about it, but many of us don’t. We all know we should have 30 minutes of exercise every day but with today’s hectic lifestyle many of us struggle to find the time. Thankfully, for the gym-phobic amongst us with memories of wet and cold cross-country days across the muddy school playing field, exercise needn’t be always about running, or going to the gym. Ever tried digging over a flower bed or veg plot? Gardening can be a great way to achieve an all-body workout. It can also be a low-impact path to being a little bit more active. Some gentle pottering in the garden (beneficial in itself) can lead to other tasks, which leads to more physical exertion, which can only ever be a good thing... But physical exercise is not the only way that gardening can help you sleep at night.
Sleep is hugely influenced by your natural circadian rhythm. Every cell in the human body has a clock that’s controlled by the suprachiasmatic nucleus (SCN) in the brain. The SCN is linked directly to the eyes. Light then, is a key driver to circadian control. Research has demonstrated if you put people into dark places with no external clues to the time of day, their circadian rhythms will become abnormal very quickly. The body needs appropriate exposure to daylight to regulate the body’s responses to help ‘reset’ this clock and keep you “on time”. Many of us spend the majority of the day inside. Light levels in an office, even close to a window, will be far below those of bright natural daylight which is around 20,000 lux. The spectrum of light inside is also quite different. Natural daylight is quite ‘blue’ (5000-6500K) and the body expects a change to more orange/red tones as the day fades to night. This is one of the reasons why ‘screen time’ in the evening isn’t good when you are supposed to be preparing for sleep. The light entering the eyes is too blue for the time of day. Spending the majority of the day inside where light levels are both low (lux levels around 150 are not uncommon) and often in the ‘warmer’ spectrum range (<3000K) is biologically confusing. Getting outside, getting a bit out of breath, and even being a bit chilly, are the best ways to regulate your body clock.
The Critical Care Research Group at the University of Oxford has been exploring how the hospital environment influences the patients’ experiences of their admission. As part of a research project (SILENCE) that was funded by the National Institute of Health Research (Research for Patient Benefit, ref: PB-PG-0613-31034), the group has been studying sleep patterns in patients admitted to the intensive care unit (ICU). The results of the SILENCE sleep study have been published in the Journal of the Intensive Care Society. Julie Darbyshire, lead researcher on the project, was also interviewed about the study for a critical care focused podcast series.
The research team used several different ways to electronically measure sleep and also asked patients and their nurses who were looking after them overnight to complete a questionnaire. All methods of sleep measurement confirmed that sleep was poor. Most patients were able to sleep for at least some of the time but the average total sleep overnight was just over two hours. This is a long way short of the seven to eight hours sleep that is recommended for most adults. The team also found that the average time a patient in the ICU can expect to be asleep before awakening is just one minute. This can leave patients exhausted by the end of the night and many feel that they haven’t slept at all.
Professor Duncan Young, senior clinical lead for the Critical Care Research Group and honorary NHS consultant in anaesthetics and intensive care medicine, said: ‘Patients clearly struggle to sleep well when in intensive care. Sleep deprivation likely leads to confusion, and confusion is thought to complicate the healing process and slow recovery. The real challenge is knowing what to do to improve things for patients.’
Julie says: ‘Patients may be offered earplugs and eye masks to help them sleep, but not everyone likes wearing them. Improving the environment has to be the better approach. This should include reducing sound levels, making sure that patients have access to plenty of natural light during the day, and turning lights off overnight.'
Julie also suggests that having access to the outside is likely to benefit patients recovering from their critical illness. Early hospital environment work by Robert Ulrich in the 1980s showed that patients who could see trees outside went home sooner and experienced lower levels of pain than those patients who could only see a wall. More recent studies suggest that access to a garden during a hospital stay can lower stress levels in both patients and their families. Recognising this, Horatio’s Garden is a charity that creates and builds accessible gardens for NHS spinal injury units and a number of hospitals around the UK have gardens where they can take their ICU patients during the day.
The team in Oxford has been able to show how different sleep in the ICU is when compared to normal healthy adult sleep patterns. As well as being awake for much of the night, patients in the ICU experience almost no rapid eye movement (REM) sleep, or deeper, restful sleep. This means that even when patients do sleep in the intensive care unit, their sleep is poor quality. Healthy sleep would include about 20% of REM sleep and about 20% of deep sleep. Good quality sleep is vital for preservation of the immune function, recovery, and can help prevent delirium which is a common problem for patients in the intensive care unit. Persistent poor sleep may also lead to longer-term cognitive and mental health problems. It has recently been reported that patients struggling to cope mentally after their critical illness can also experience worsening physical health .
Gardening is, in and of itself, a positive, forward-looking activity. After all, no-one plants carrot seeds without expecting to eat carrots in the future! The Kings Fund report on Gardens and Health (2016) highlights some of the mental health benefits to just being in a natural environment, GPs in Scotland are working with the Royal Society for the Protection of Birds to offer ‘nature prescriptions’ in Shetland, and the Royal Horticultural Society (RHS) has teamed up with GPs across the UK as part of a new ‘social prescribing’ scheme. The University of Oxford Gardens, Libraries and Museums (GLAM) project for well-being is looking at this in more detail. Researchers from the Centre for Evidence Based Medicine (Nuffield Department of Primary Care Health Sciences) are working with GLAM to promote knowledge exchange, raise awareness, and to add to the evidence base to support wider implementation of social prescribing.
This year’s Chelsea Flower Show has a strong focus on the health benefits of interacting with nature. Many of the show gardens feature gardening for resilience, recovery, and wellbeing. So if you’re struggling to sleep at night, go outside during the day, plant some seeds, prune something, dig the borders, enjoy the fresh air and the sunshine, and reap the rewards of a good night’s sleep.