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I hope you’ve all had wonderful relaxing breaks and ready to face whatever 2025 may bring.
The winter is traditionally a time for colds and flu, so I’m focusing this week on ways that lighting and plants can support you immune system and even help you to breathe more easily too. I’ve included some dates of conferences you might want to think about too.
Thank you for reading this – and giving me a reason to write!
Feeling under the weather?
You’re up to 20% more likely to call in sick on a Monday, and the day after Christmas is the most popular sick day, according to Fast Company’s analysis of searches for their blog ‘Top tips for calling in sick even when you’re not.’ – The most common days for people to call in ‘sick’ aren’t what you think.
But there is a good chance you might be feeling under par.
Your immune response is lowest in winter – regardless of where you live. Interestingly, that pattern is not linked to climate as there are seasonal variations in immune response even in equatorial zones where day length and temperature remain roughly the same all year round – Seasonal and daytime variation in multiple immune parameters in humans: Evidence from 329,261 participants of the UK Biobank cohort.
You probably feel at your worst when you wake up: your inflammatory response is greatest during the night and into the early hours – Twenty-four hour pattern in symptom intensity of viral and allergic rhinitis: Treatment implications.
So can light help?
It’s tempting to spend all day in bed with the curtains closed, especially as photosensitivity is a common symptom of flu – Influenza.
But getting enough light during the day and darkness at night will help to boost your mood, give your immune system a helping hand and can reduce risk of hospitalisation among children, too – Effects of influenza vaccine and sun exposure time against laboratory-confirmed influenza hospitalizations among young children during the 2012–13 to 2015–16 influenza seasons.
One study found a direct link between higher daytime light exposure, specifically blue-enriched lighting and COVID-19 status in young adults – Light exposure predicts COVID-19 negative status in young adults. At the other end of the lifespan, brighter days improves resistance to the flu virus in dementia patients living in residential care, too – Preliminary evidence that daily light exposure enhances the antibody response to influenza vaccination in patients with dementia.
Getting some natural daylight – especially if you can wrap up warm and get outside, will not only boost your immune system and speed your recovery time – Sunlight and Protection Against Influenza, it will reduce your risk of spreading your bugs to your loved ones, partly thanks to the UV and infra-red wavelengths that can be blocked by glazing:
If you do need to spend time with family or colleagues, especially if they may be infectious, plan your activity around the middle of the day; you will be most alert and your immune system will be strongest too – Circadian immune circuits.
I can’t promise you’ll want to go to work, but making sure you get enough bright light during the day, especially daylight, will help you keep those bugs at bay.
Dates for the diary…
Excited to see applications open for IALD Enlighten Europe in Valencia, Spain, from 26 to 27 June 2025. If you don’t already have an account on the IALD digital platform, sign up for IALD event notifications here.
It’s National Houseplant Appreciation Day!
I’m a huge fan of house plants – here are photos of some of mine
The presence of indoor plants can increase how attractive and healthy we feel a space to be – and even boost our perception of air freshness and thermal comfort. ‘Green’ v ‘lean’ spaces boost mood, engagement and performance in every sector, from workplace – The appearance of indoor plants and their effect on people’s perceptions of indoor air quality and subjective well-being, healthcare – Stress-reducing effects of indoor plants in the built healthcare environment: The mediating role of perceived attractiveness, and schools – The Impact of Interior Plants in University Classrooms on Student Course Performance and on Student Perceptions of the Course and Instructor.
Plants can also improve humidity levels, which in turn can help with dry and itchy eyes from long hours at the computer in a heated space
So how much green do you need?
Everyone is different – and millions of people experience anxiety about insects or contamination, so you can’t assume everyone will embrace a spider plant.
But one study found that two-thirds of participants preferred 8% by volume, but just 0.5% was enough for everyone else – The effect of three different volumes of indoor greenery on employee well-being.
Photographs of nature will help, especially if you choose images with complex colour transitions – it turns out the fractal quality of those patterns is key to their restorative appeal – Visual properties and perceived restorativeness in green offices: a photographic evaluation of office environments with various degrees of greening.
Just seeing pictures of greenery and plants could help you to make healthier choices and reduce your cravings for sugary snacks – Indoor nature integration for stress recovery and healthy eating: A picture experiment with plants versus green color.
Another reason to celebrate your green companions today!