Winter Solstice

Lux chart

December 21st marks the northern hemisphere’s astronomical beginning of winter, both the shortest day and the longest night of the year. In Edinburgh, Scotland, that means only 6 hours 56 minutes of daylight and a long 17 hours 4 minutes of night. Even with good weather — and we were lucky get several hours of blue sky and sun this time — the angle of the sun is so low to the horizon that its rays are relatively weak. I measured approximately 40,000 lx of direct sunlight near midday. As you can see from the lux chart above that is still a good level of light versus staying indoors, so do get out for some fresh air and a walk if you can!

The good news is that each successive day will begin growing ever longer and brighter as our planet continues its arc around our star, tilting northern hemisphere dwellers back towards the sun, giving us all a better chance at catching some of that extra day light. Happy winter solstice!

Wearable Futures

Wearable Futures

Wearable Futures is a large two-day event held in London at the impressive Ravensbourne college, next to the O2 dome. With 50 speakers and 300 attendees it was a busy event running dual presentation tracks in parallel for most of each day.

I had the opportunity to present Light Log as part of their wearable health panel, along with speakers Duncan Fitzimons, Kuniharu Takei, Ivor Williams, and chair Nic Howell. Kuniharu had a particularly leading edge area presentation covering smart bandages, where he is researching and prototyping smart materials that act as joint sensor, display, and are capable of releasing drug treatments when needed (diabetes being one of the early target conditions being investigated).

The Light Log Wearable Futures Presentation had a 10min slot in the panels discussion, followed by audience and panel member question and answers. The discussion panel’s time seemed to race past very quickly – it would have been great to have longer for audience questions – so thanks to all those of you who came up and caught me after the discussion panel to talk about Light Log!

Measuring Colour

Colour temperature vs. tint

With seasonal affective disorder and winder blues, light lux (the total light energy in the human visible spectrum), is the main component needed to be measured and tracked over time. However, recording the light colour components also has important benefits for analysis. First, it allows improved automatic tagging for light environment types, where the colour temperature and colour tint allow a better characterisation of the kind of light you’re being exposed to (e.g. fluorescent office lighting vs. natural outdoor light, or bright but overcast days vs. clear blue sky days). This extra information can be used to generate high level, dashboard like views of each day, week, month and year – do you know how many hours of direct sunshine you had this week? The second use of colour data is in measuring the amount of the shorter wavelength (blue) light you are exposed to. Studies suggest blue light is more effective at triggering cells in your eye’s retina responsible for maintaining your circadian rhythm – stimulating serotonin production and inhibiting melatonin, keeping you alert and clear during waking hours. Avoiding blue wavelengths for a few hours before you try and sleep allows melatonin levels to naturally rise, helping you have restful, refreshing sleep.