Light and cell signalling, light and pain control – and light and laughter

Circadian Neuroscience webinar

Achim Kramer, one of the pioneers of Circadian Medicine is presenting live on Monday 28th of April as part of the outstanding – Seminar Series “Current Topics in Visual & Circadian Neuroscience” organised by the Translational Sensory & Circadian Neuroscience Unit (MPS/TUM/TUMCREATE) led by Prof. Dr. Manuel Spitschan. The 60-minute (45 min. talk + 15 min. Q&A/discussion) graduate-level seminars are free to join and take place via Zoom. 

I’m hoping Achim will talk about his recent Nature paper on the critical importance of circadian rhythms for healthy cell signalling and tissue growth, or his ground-breaking use of bioluminescence to track circadian rhythms in the fetus – Circadian coupling orchestrates cell growth, Circadian clock activity in human umbilical vein endothelial cells of preterm and term neonates.

Either way, it should be a fascinating hour.

Next weeks’ session looks excellent too, with Takumo Morimoto from Oxford University talking about his work on perception and colour, with clear implications for spectral tuning for lighting professionals – Colour expectations across illumination changes.

The sessions are recorded so you can listen again – but I love the energy when you’re online ‘live’ – and the chance to ask questions from these amazing scientists is unique. 

Light pain relief 

I’ve signed up for a half marathon – I’m a ‘use or lose it’ kind of girl.

Everything was going fine.

Steadily improving my times and feeling very smug.

Then my right knee started to hurt.

A bit at first. I decided to soldier on – no pain no gain, right?

But after Park Run last Saturday, I could hardly put any weight on it at all.

Wincing with every step, I suddenly felt very old.

And I’m not alone

An estimated 24% of the UK adult population have some form of disability, with around half of those related to mobility –  UK disability statistics: Prevalence and life experiences. In the USA, more than one in ten have serious difficulty walking or climing stairs – Disability Impacts All of Us Infographic.

People who struggle to move around are more likely to suffer from loneliness, increasing risk of dementia by up to 31% – Loneliness linked to dementia risk in large-scale analysis.

There’s a bidirectional relationship between loss of mobility and cognitive decline – moving around freely, especially fast walking, gives your brain a work-out too. At the same time, loss of mobility, especially in the lower body, can be a valuable early warning sign of neurodegenerative disease.. – The Relationship Between Mobility Dysfunction Staging and Global Cognitive Performance, The relative temporal sequence of decline in mobility and cognition among initially unimpaired older adults: Results from the Baltimore Longitudinal Study of Aging.

Of course, you could just pop a pill or two.

But the side-effects of painkillers can be just as devastating, especially when combined with other drugs, with nausea, weakness and other symptoms chipping away at confidence and quality of life at home and productivity at work – Self-reports of medication side effects and pain-related activity interference in patients with chronic pain. Drugs are bad for the planet, too, with medicines accounting for up to half of a country’s healthcare carbon footprint – Carbon footprint of oral medicines using hybrid life cycle assessment.

Here’s where light, starting with access to daylight and views can help – Looking for a Beam of Light to Heal Chronic Pain.

Pain has a circadian component: different types of pain are worse at different times of day – Circadian pain patterns in human pain conditions – A systematic review, perhaps due to the impact of hormones like cortisol and melatonin on baseline sensitivity – Pain Perception in Healthy Young Men Is Modified by Time-Of-Day and Is Modality Dependent. Circadian disruption reduces our tolerance for pain, and increases recovery time – Circadian Disruption in Critical Illness, Systems and Circuits Linking Chronic Pain and Circadian Rhythms.

Increased exposure to sunlight after spinal injury can reduce stress, perceived pain and pain medication use – The Effect of Sunlight on Postoperative Analgesic Medication Use: A Prospective Study of Patients Undergoing Spinal Surgery, while another study found a reduction in length of stay by up to 41% in rooms enjoying increased levels of natural light – Impacts of indoor daylight environments on patient average length of stay (ALOS) in a healthcare facility.

One of the benefits of sunlight may be the presence of infrared wavelengths, a promising avenue for non-pharmacological topical pain relief – Infrared Radiation in the Management of Musculoskeletal Conditions and Chronic Pain: A Systematic Review.

But artificial light can offer a valuable boost, especially in the winter months. A growing number of studies suggest that an hour of bright light in the morning can reduce pain perception and volatility ‘flares’, improve function and sleep – Morning Versus Evening Bright Light Treatment at Home to Improve Function and Pain Sensitivity for Women with Fibromyalgia: A Pilot Study, Morning Bright Light Treatment for Chronic Low Back Pain: Potential Impact on the Volatility of Pain, Mood, Function, and Sleep.

Dark nights are as important as bright days, with a clear link between light levels as low as 40 lux (an average tablet, depending on the size) and disrupted sleep, mood and recovery times – Timing of light exposure affects mood and brain circuits, The ecological impacts of nighttime light pollution: a mechanistic appraisal, Let there be no light: the effect of bedside light on sleep quality and background electroencephalographic rhythms.

Bottom line.

My creaky knees are a long long way away from the crushing chronic pain that so many endure every day. But I do know that lighting can help. 

1. Bright days and dark nights set the body clock, improving sleep, tolerance and volatility.
2. Harness that natural rhythm to target the type and timing of medication, optimising the benefits while reducing the dose.
3. And find a window – or better yet get outside – for full spectrum relief.

Laughter is the best medicine 

There is good evidence that distractions increase pain thresholds – it doesn’t really matter what the distraction is. But humour has the added benefit of boosting mood compared to a documentary for example – and can be a valuable antidote to the inevitable anxiety and catastrophising linked to chronic pain – Laughing away the pain: A narrative review of humour, sense of humour and pain, Effects of mirthful laughter on pain tolerance: A randomized controlled investigation. There’s more research in children, with evidence that clown therapy can help to relieve pain perception, crying and length of hospital stay – Effectiveness of clown intervention for pain relief in children: A systematic review and meta-analysis.

So how can lighting help? 

1. Eye contact makes us more likely to share a smile – in the West at least – I looked at you, you looked at me, I smiled at you, you smiled at me—The impact of eye contact on emotional mimicry. We’re more likely to trust the other person, too – Direct Speaker Gaze Promotes Trust in Truth-Ambiguous Statements. So make sure you can see each other clearly, especially important for older adults who may struggle with focus and sources of glare.
2. See them in a warmer light. Lower CCT significantly reduces negative response bias, so opt for softer lighting if you’re in the mood for gentle banter – Effects of illuminance and correlated color temperature of indoor light on emotion perception.
3. Turn up the volume. Bright light tends to intensify emotional responses, good and bad, although the effect depends on gender and baseline conditions – Effects of illuminance and correlated color temperature on emotional responses and lighting adjustment behaviors. People with depression, or simply thinking sad thoughts, tend to perceive spaces as dimmer. So choose a well-lit space (ideally by a window) for clowning around to raise a smile and help to get some perspective – Ray of Hope: Hopelessness Increases Preferences for Brighter Lighting.

Beltane – the Bright Fire Festival

An ancient pagan festival marking the half-way point between summer and winter solstice, the old rituals turn out to have a grain of truth – when it comes to light at least.

1. Emerging from the ‘Vitamin D Winter’: By Beltane, the sun is high enough in the sky here in the UK (above 45° at midday) for UVB radiation to activate vitamin D synthesis in the skin, boosting immunity, mood and fertility.
2. Dawn connection: Watching the sun come up improves sleep at night, thanks to the rapid rise in light levels, improving sleep, metabolism and recovery – The importance of residential dusk and dawn light exposure for sleep quality, health, and well-being. 
3.  Solar alignment: Our ancestors oriented sacred structures and stone circles to greet the sun at this precise moment in the year.  A celebrated example in Ireland is the Beltany Stone in Donegal – Shadows and Stone Blog.