London - People should fit blackout blinds and ban electronic gadgets from the bedroom to avert the risk of diseases such as cancer, experts say.
Cutting out all light sources while we sleep could halt damaging interruptions to our body clock, they believe.
Learning to love the dark more means we can help prevent changes to our internal rhythm – which has been linked to health problems such as cancer, diabetes, depression and even obesity.
Breast cancer researcher Richard Stevens said we need to ‘appreciate’ the gloom – even dimming household lights in the evenings to help the brain and body get ready for sleep.
He said: ‘The point to emphasise is that while sleep is deeply important to wellbeing, so too is exposure at night to dark.
‘The importance of sleep has finally entered mainstream thinking and practice; however the importance of dark is still greatly under-appreciated.’
Dr Stevens, of the University of Connecticut, said body clocks have evolved to respond to the daily pattern of sunlight. Hormone production, the work of genes, body temperature and metabolism all follow a pattern set by the sun.
Electric light, in contrast, is ‘dim and ill-timed’ and may cause disruption. Along with blackout blinds, he recommends banishing tablet computers from the bedroom because they emit ‘blue’ light that keeps us particularly alert. And if we have to get up in the night, we should use lights fitted with a dim red bulb.
Writing in the journal Philosophical Transactions B, published by the Royal Society, Dr Stevens warned of the huge dangers of keeping streets and homes artificially lit.
He said children, including babies in the womb, may be particularly vulnerable because they are still developing, adding: ‘Excessive lighting of the night sky is as important an issue as climate change.’
He also urged for precautions to be taken while long-term damage to health is being assessed.
It thought that disruption to body clocks suppresses the production of melatonin, a hormone that helps keep breast tumours in check. Studies have shown women night-shift workers to be at higher risk of breast cancer, while working odd hours has also been linked to an increased risk of prostate and bowel cancers.
Other research has raised concerns about night-time light and diabetes, depression and obesity. Separate research in the same journal shows that street lighting also affects wildlife.
Studies by Exeter University found plants took longer to flower and robins sang at night and during the day in urban areas such as Glasgow.
Researcher Dr Fiona Matthews said street lighting and the intensity of home lighting had grown enormously over the last few decades. ‘We urgently need to reverse this trend,’ she said.
Daily Mail