You are what you sleep

Margaret Thatcher was once famous for promoting the adage that she could thrive and work effectively on only a few hours sleep per night.

And, though there are exceptions to every rule, for the large majority of us it is not the same - we ignore sleep at our peril.

A report today for the BBC's ‘Day of the Body Clock’ asserts that society has become ‘supremely arrogant’ in ignoring the importance of sleep.

Leading researchers from Oxford, Cambridge, Harvard, Manchester and Surrey universities have warned that cutting back on sleep is leading to serious health problems.

Scientists have warned that our modern life and 24 hour society mean many people are now ‘living against’ their body clocks with damaging consequences for health and well-being.

We all know that lack of regular sleep can affect our mood, vitality and energy levels. But cancer, heart disease, type-2 diabetes, infections and obesity have also all been linked to reduced sleep.

Prof Russell Foster, from the University of Oxford, told the BBC that people are now getting on average between one and two hours less sleep a night than 60 years ago.

"We are the supremely arrogant species because we feel we can ignore the fact that we have evolved under a light-dark cycle,” he said.

“What we do as a species, perhaps uniquely, is override the clock. And long-term acting against the clock can lead to serious health problems.”

Regular readers of ‘The Lighthouse Keeper’ will know that the natural rhythms of life, and of light and darkness, have been discussed at frequent intervals.

Harvard University’s Prof Charles Czeisler confirmed that light is the “most  powerful synchroniser” of our internal biological clocks.

He said energy efficient light bulbs as well as TVs, smart phones, tablets and computers had high levels of light in the blue end of the spectrum, which is "right in the sweet spot" for disrupting the body clock.

“Light exposure, especially short wavelength blue-ish light in the evening, will reset our circadian rhythms to a later hour, postponing the release of the sleep-promoting hormone melatonin and making it more difficult for us to get up in the morning.

“It’s a big concern that we're being exposed to much more light, sleeping less and, as a consequence, may suffer from many chronic diseases.”

In ‘Blinded by the night’ I noted that an increasing number of scientific studies were questioning the long-held premise that humans are largely immune to the effects of artificial light at night.

Today, or to be correct, tonight, we have levels of light hundreds and thousands of time higher than the natural level during the night – and light pollution is currently rising by a general average of 20 percent a year.

What is happening in the streets outside our homes is not always within our control. But we can take more personal responsibility when it comes to the light behind closed doors.

In his book ‘A Great Day at the Office’, Dr John Briffa discusses sleep as one of the strategies to help maximise our energy and performance levels.

“Light exposure in the day promotes better sleep but it may have the reserve effect late in the evening,” he says.

“In one study, light exposure from room lighting was found to delay meltonin exposure by about 90 minutes. Turning room lighting down, or perhaps off altogether (and using dimly lit lamps) during the evening may help sleep.”

I covered the topic of how excessive light at night affect our sleep and health more extensively in ‘Early morning birdsong’.

If you don’t sleep too well at night then it is probably a good idea, according to Dr Briffa, to be mindful of the potential impact of evening light levels on sleep.

TVs, laptops, tablets and smart phones - with their blue-rich light - can all suppress melatonin function too so avoiding the use of these within a couple of hours of bedtime may be a helpful - though impossibly hard - tactic to implement.


The Lighthouse Keeper is written by Clive Simpson - for more information, commission
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