Monday 29 January 2018

Let there be light

Tuesday is my busy day at work, I have wall-to-wall classes with barely enough time for lunch and Wednesday starts sharp at 0900hrs with Cell Biology practicals. The new home schedule is that The Beloved is looking after her aged father Pat the Salt on Tuesday nights, so all the Tuesday farm work falls to me. Last Tuesday, I had to call in to the feed-store on my way home and buy six bags of #3 sheep muesli for our recently increased flock of ewes - they are starvin' poor cr'atures for want of grass. It was 1745 and dark by the time I pulled into the yard and I was faced with a choice: a) move the two feed-troughs to Crowe's and empty in a half sack of sheep feed or b) do it in the dark before leaving for work in the morning. There was a sliver of moon in the sky and it wasn't raining to I went for a).  Now if I'd dropped my keys, things would have been difficult but I could "see" the troughs loom up as a darkness on the dark grass and I was able to shift them, fill them and count the sheep as they fed. That must be the reason we prefer white sheep!  But I was careful not to take any short-cuts through the hedges - a poke in the eye with a sharp stick is no fun. That's sort of amazing, how effective our eyes are even when photons are few and far between.

It turns out, however, that some light is better than other light and sun-light isn't ever-and-always the best. Most people are aware that we can make enough vitamin-D if we get enough sunlight; and if we fail to get enough vit-D there are dire consequences for calcium balance and bone-integrity. I wrote in 2015 about how not enough day-light seems to be driving a myopia epidemic: it's the dopamine, stupid. Like every other living thing on the planet, we have been crafted by millions of years of evolution to use environmental cues to help run our lives. The author of Ecclesiastes knew this "To every thing there is a season, and a time to every purpose under the heaven . . . a time to break down, and a time to build up" KJV.  If we run around at high-doh 24/7, then we rapidly run out of steam and succumb to tremors, cancer and an early death. I heard on the wireless last week that in 1980, the average teenager slept for 9.5 hours a night but that has slipped to 6.5 hours a night for 2015. But I'm not going to rant about smart-phones, the tyranny of popularity or cyber-bullying in the bedroom.

I am rather going to cue on a worrying piece to camera in Nature by Karolina Zielinska-Dabkowska (with that name, no surprises to hear that she's Polish - working in Gdansk). She's an expert on lighting design, so she might be tempted to see all the woes of the world through the tints in her own spectacles - like all my understanding of the natural world and human physiology is prefaced by "over millions of years of evolution". But her arguments have, for me, the ring of consistency and truth. I've mentioned how 10% (and rising) of the world's electricity goes to support server-farms and the Interweb, Dr KZ-D now tells us that 20% goes out for lighting.

That was worrying - to Fidel Castro; to the EU; and others - and so the incandescent light-bulb was fingered as the low-hanging fruit. These light-bulbs have been around for more than 100 years and so are a known, tried and tested, product. But they are hungry on the power. So there was a move to replace them all with CFLs = compact fluorescent lamps which, according to the packaging, gave the equivalent of 100W of incandescent light for about 20 W of power. Win! they were a bit cranky on the start up but lowered everybody's electricity bills; albeit by shunting the cost of the new product onto the housekeeping budget. You cannot buy incandescent bulbs in Ireland now, except maybe on eBay. Win, maybe, but definitely not win-win: because the new technology contained significant amounts of mercury and nobody thought through the disposal protocol - perhaps because the CFLs were marketed as lasting forever. So these delicate glass-and-metal receptacles are sent to land-fill where they break and leach mercury into the landfill sump. Should we take out a class-action suit against Philips and GE because their solution to save energy will brain-damage our grand-children?

But maybe more damaging, because insidious and a known-unknown, is the difference in the emitted spectrum of incandescents vs CFLs; especially insofar as it affects the hormones of our sleep-wake cycle. Without hours of darkness, we don't carry out a range of repair-and-polish activities in our brains and elsewhere. Sure, it's about getting enough dream-time, so that we can process, integrate and de-tox the events of our troubling day but that is by no means all that is controlled by the balance of melatonin and cortisol. The picture [L], modified from KZ-D's article, shows that incandescent lights, which are switched on as twilight falls, are a remarkably good fit with natural evening light. CFLs otoh are too rich at the blue end of the spectrum and have effectively no sunset red.

That turns out to be a Big Problem because of the photo-pigment melanopsin, which is super-sensitive to light at 480 nm = plunk in the middle of visible 'hello sky' blue. Melanopsin is the pigment in retinal cells interspersed among the rods and cones called intrinsically photosensitive retinal ganglion cells - ipRGCs to their friends. These cells react to the the presence of blue light at day-break and no blue light at sunset to control the release of cortisol, melatonin, dopamine and serotonin. These lads have a finger in a wide range of physiological and psychological pies: alertness, appetite, blood pressure, immunity, mood, metabolism and temperature. Blue light at night = shepherds take fright. Dr KZ-D'd advice:
  • lights OFF at night
  • get an hour of real day-light on waking in the morning
  • no CFLs at all at all
The Blob's corollary: get up in the dark, switch on the CFLs and blog like a mad-thing for a couple of hours before work . . . you'll be wired!

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