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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Early morning birdsong

Lighthouse on the cliff tops of Cromer, Norfolk.                                       Photo: Clive Simpson

Are you sleeping well on these long end of winter nights? If not then part of the answer may be in how dark your bedroom is.

As we travel through winter, with its emerging hint of longer days and promise of spring, it is appropriate to revisit the theme of some previous blog articles about night, darkness and the effect of artificial light on our modern lives.

The other morning I awoke midway through the night at around 3 am to hear birdsong outside. Normally a welcoming sound but at that hour, and with dawn still some four hours away, a little disconcerting. 

Birds singing during the ‘night’ is no longer such an infrequent occurrence. It is a somewhat troubling development and perhaps an indicator of wider factors at play. 

The birds it seems are often duped by our brightly lit streets, on-off ‘security’ lights and other forms of night-time illumination and general light pollution, into thinking daylight has arrived early.

And here’s the thing. All of us, birds included, are hard-wired to sleep in darkness, not in bedrooms full of light, computer monitors, digital alarm clocks or TV stand-by lights.

Chronic exposure to light at night is bad and, to understand why, we need to look into the past. Prior to the end of the Stone Age, humans were largely exposed to just two different kinds of natural light.

During the day we had the sun, while at night we had the moon and the stars, and perhaps the light from campfires. The binary day/night pattern was unrelenting, and our biological programming followed suit.

So why can't you get a good night's sleep? The problem is that many of us probably don't realise what makes us fall asleep in the first place. 

Compared to our ancestors our bodies’ circadian rhythms now also have artificial lighting at night (LAN) to contend with. Indoor lighting may be considerably less powerful than sunlight but it is certainly many orders of magnitude greater than star and moonlight. 

Melatonin suppression is key to understanding much of why LAN is bad for us, particularly in the winter months of the northern hemisphere.

This workhorse biochemical is produced at night when it is dark by the brain's pineal gland  to regulate our sleep-wake cycle. It lowers blood pressure, glucose levels and body temperature — key physiological responses responsible for restful sleep. 

The part of our brain that controls the body’s biological clock is known as the Suprachiasmatic Nucleus (SCN), a group of cells in the hypothalamus which respond to light and dark signals. 

The optic nerves in our eyes sense light and transmit signals to the SCN telling the brain when it is time to wake up, which also kickstarts other processes, like raising body temperature and producing hormones such as cortisol. 

Normally our cortisol levels are relatively low at night - allowing us to sleep - and higher during the day, allowing for the stabilisation of energy levels and the modulation of immune function. 

But LAN unnaturally elevates cortisol levels at night, which can then disrupt sleep and introduce a host of problems relating things like body-fat levels and insulin resistance. It also contributes to sleep debt and can disrupt the regulation of appetite.

If, on the other hand, our rooms are properly dark at night there is no optic signal to the SCN, so our bodies pump out the much needed melatonin. 

Light exposure during the previous day can also affect melatonin levels - studies have shown that exposure to bright room light before bedtime shortens melatonin duration by about 90 minutes compared to dim light exposure. In addition, exposure to room light during usual hours of sleep suppresses melatonin levels by more than 50 percent. 

So, even before you hit the hay, the light in your bedroom may be causing you problems. With the introduction of tablets (not the sleeping kind), smartphones, and energy-efficient LED light bulbs, it's an issue that's only getting worse. 

And just to add insult to injury, many modern LED (light-emitting diode) devices emit blue light which is especially good at suppressing melatonin. This is because melanopsin — a photo-pigment found in specialised cells of the retina involved in the regulation of circadian rhythms — is most sensitive to blue light. 

Regrettably, all this hormone and biochemical disruption is creating downstream effects — and studies are now showing correlations with weight gain problems, the incidence of cancer, depression and adverse effects on the immune system.

Essentially we need to keep our bedrooms as dark as possible and avoid blue light before sleep. 

You might want to think about this next time you leave even the dimmest lights on in your bedroom overnight — including your clock radio and the light that bleeds in through the curtains from nearby street lights. 

Why not try removing electronic equipment from the bedroom and using dimmer lights before before you turn in, as well as refraining from viewing TV, smartphones and computer screens for up to an hour before bed?

And if your bedroom is affected by artificial light from outside (and blackout curtains don’t do the trick) speak to your local council about street light shielding, and maybe your neighbour about realigning any problematic external floodlights.

Oh, and while we’re at it, switch off that bl**dy lighthouse! Sleep well, zzz zzz.

The Lighthouse Keeper is written by Clive Simpson - for more information or to get in touch click here