Ever been doggedly awake at 3am, willing your mind to quieten against the dread tick, tok of the clock and increasing proximity to dawn? Humans are useless without sleep; in fact, biometric tracking has found sufferers of inconsistent sleep are significantly less resilient, physically and mentally. Elements of sleep disfunction are associated with all mental health disorders, but irregular sleep-wake times (less than 90mins difference daily) are linked to poor quality sleep, mental health decline and sadly, are a core marker of suicide.

Sleep patterns depend on circadian rhythm – the body’s equivalent of a 24hr clock – and it controls not just how awake you are, but hormone release, metabolic function and body temperature. It’s a sensitive instrument and takes a while to adjust to new timings. Sufferers of jetlag will know how brutal it can be to persuade your body into a new time zone. When your internal clock is skewed, you miss restorative sleep; the kind essential for mood regulation and immune responses.

Unfortunately, artificial light is a rhythm killer. Sir Davy’s first arc lamp and Edison’s lightbulb illuminated new ways of living; doing what we want, when we want and markedly reducing home fire risks. We’ve taken to freedom with enthusiasm but are over lighting beyond the needs of the task, casting brightness into every shadow. Indoor lighting is personal choice, we can choose when to switch off (hard with a particularly bingeable Netflix series though). Outdoor light is a community issue however, and the brightening of the night sky is, ironically, causing invisible harm.

A 2016 study found nearly 100% of the British population lives under light-polluted skies. The rapid pace at which night skies were being lost prompted the formation an all-party Parliamentary Group www.appgdarkskies.co.uk who have issued a UK policy plan to include consideration of lighting into decision-making processes across sectors.

Guidance on modernising outdoor lighting is provided by the Institute of Lighting Professionals on their website, but for lay-people the advice is simple:

1. avoid installing additional external lighting
2. where it is required, ensure lighting only illuminates the necessary area
3. position lights so you need the fewest number
4. use the lowest practical lumens (brightness) to achieve your purpose without detriment to the task
5. use shields, hoods and louvres to angle light exactly where needed
6. mitigate internal light spill by turning off unused lights and closing curtains
7. use movement sensors or timers to minimise the time lights are on
8. take particular care in ecologically sensitive areas e.g. near ponds, lakes, rivers and areas of high conservation value (that’s most of the green space in this area)

Haslemere Biodiversity, a grass roots conservation group, have been looking at adverse effects of obtrusive light on native wildlife. Day-time flora and fauna are disturbed by artificial light, but effects are best documented in nocturnal species such as bats. These tiny mammals rely on darkness to avoid predators, reduce competition for food and to conduct courtship rituals.  Just like us, their circadian rhythm maintains natural cycles of hormone production, and disrupting those natural patterns interferes with ovulation and embryo development. For some species lights are a sensory barrier they cannot move through, effectively cutting off habitats. Frogs, toads, invertebrates and songbirds such as the Punchbowl’s nightjar are all affected; artificial lights impede their ability to navigate, forage and breed which reduces and fragments populations.

To our south the South Downs National Park was designated an ‘International Dark Sky Reserve’ in 2016, one of only sixteen such reserves worldwide. Haslemere is similarly ahead of the curve with a Dark Skies Policy that asks properties outside settlement boundaries to deliver very low lighting in keeping with conservation areas. Central areas such as shops, main roads and places with significant pedestrian use are recognised as zones needing higher light levels.

Like Haslemere, Grayshott is surrounded by beautiful countryside, shared with a variety of wildlife. If you’ve ever wanted to see bats or owls in the wild, we live in a great spot for it. Tiny pipistrelle bats are seen nightly at the recreation ground in the warmer months and if you’re lucky (and have keen eyesight) there are long eared brown bats there too. Take pillows and blankets out at dusk and settle down near the tree line at the north end to spot them flying in and out of the trees. If Strigiformes are more your thing, stroll down Stoney Bottom at dusk, wait for the day birds to quieten down and five minutes or so later the vocal community of owls will start their calls.

Balance is a recurring theme in life; too little of something vs too much, ying and yang, work and play. Adjusting attitudes to light and dark needs balance too. A little thought about where light is really needed and how bright it should be. If you’d like to know more about effects on wildlife (particularly when putting up Christmas lights, where colour really does matter) or you are interested in helping community efforts, don’t hesitate to contact Haslemere Biodiversity, your friendly local conservation group at info@haslemerebiodiversity.org.uk or visit www.haslemerebiodiversity.org.uk.