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Light for Long-Covid – and the link between darkness and hearing loss

A YouTube channel for long drives

For those of you hitting the road, this is a classic episode by the brilliant Professor Samar Hattar – but you can’t really go wrong with these – Translational Sensory & Circadian Neurosci Unit



The long road to recovery from long Covid 

Maybe you, a colleague or a loved one are among the 65 million people worldwide – Long COVID: 3 years inand an estimated 7% of Americans  Nearly 7% of Americans struggle with Long COVID as infections surgewill wake up today struggling with the legacy of COVID-19 infection: grinding fatigue, brain fog and muscle pain – Long COVID: major findings, mechanisms and recommendations.

This topic is close to my heart: I spent years recovering from post-viral syndrome myself, with very similar symptoms, including extreme photosensitivity.

I intuitively experimented with light and darkness to manage pain, improve focus and mood – and finally enjoy restful sleep again. That journey led to my work today, so I have been fascinated to discover a crop of brilliant new research that confirms these links in four critical domains

1.  COVID-19 infects and replicates in the retina, altering photosensitivity and undermining the critical non-visual signalling pathways that regulate sleep, mood and attention – SARS-CoV-2 infects and replicates in photoreceptor and retinal ganglion cells of human retinal organoids.

2.  This virus is also linked to reduced cortisol response: the natural complement to melatonin, triggered by exposure to bright light that also regulates inflammation and the immune response –  Physiology, CortisolThe effects of light exposure on the cortisol stress response in human males.

3.  This hormone reduction effect extends to the serotonin cycle, with reduced uptake –  Serotonin reduction in post-acute sequelae of viral infectionRegulation of serotonin, also known as the ‘happy hormone’ levels is directly linked to bright light exposure – Chapter 1 – Evolution of serotonin: sunlight to suicideMulti-Level Processes and Retina–Brain Pathways of Photic Regulation of Mood.

4.  Finally, while people suffering from post-viral syndrome and chronic fatique may spend many hours in bed, they rarely feel refreshed on waking. In ‘normal’ sleep, your relaxation response – the parasympathetic nervous system –  takes over.  But for those with post-viral syndrome and CFS/ME, the opposite is true – Research progress in the treatment of chronic fatigue syndrome through interventions targeting the hypothalamus-pituitary-adrenal axisMelatonin, the ‘hormone of darkness’ is directly linked to the parasympathetic nervous system – Peripheral and Central Effects of Melatonin on Blood Pressure Regulation.


How can light help?

1. Maximize Natural Light Exposure:

   – Spend time outdoors each day, especially in the morning if you’re strong enough to get outside. Otherwise, just sitting by an open window will help.

   – Open curtains and blinds to let natural light into your living space.

   – Place furniture – your chair or dining table – close to the window so you stay connected with the outside world.

2. Use Light Therapy:

   – Consider using a light therapy box, especially during darker months or if natural light is limited. Aim for 20-30 minutes in the morning to boost mood and improve sleep.

3. Optimize Indoor Lighting:

   – Use bright, cool white lights during the day to promote alertness.

   – Switch to warmer, dimmer lights in the evening to signal your body it’s time to wind down.

4. Limit Blue Light Exposure Before Bed:

    – Reduce screen time from phones, tablets, and computers at least an hour before bed.

    – Try a podcast, guided deep breathing or gentle exercise to get your parasympathetic nervous system back on track.

5. Create a Restful Sleep Environment:

   – Ensure your bedroom is dark and cool. Consider blackout curtains to block out any disruptive light.

   – Maintain a regular sleep schedule by going to bed and waking up at the same time each day, even when you wake up still feeling tired. I found 20-minute naps during the day to be a great solution.

And add a touch of sparkle and joy – fairy lights, coloured strips or a spotlight onto a disco ball, a or a favourite photo can transform the atmosphere at the flip of a switch.


I know from personal experience that light can be a surprisingly powerful ally in the long road to recovery from post-viral syndrome and Long-COVID.  Natural light, complemented by artificial light, simple playful touches and a calm, dark space to rest, can improve sleep, mood, and energy levels so that you can see the light at the end of the tunnel.


Sunglasses shopping.. 

Over here in the UK, thoughts are turning to the summer break and sunglasses sales peak – but which ones should you buy?

Here’s a quick guide on how they work and what to buy without breaking the bank.

Four main types:

•  Polarized: Light is a particle, it’s also a wave, moving like a corkscrew spiral through space. Polarised lenses block parts of that spiral, reducing glare, especially outdoors on snow, sand or water.

•  Photochromic: Invisible microcrystalline silver halides are embedded in the lenses. UV-A light (320–400 nm) from sunlight triggers a reaction to form elemental silver, which is visible, so the lenses look darker. The silver goes back to its invisible state in the absence of those intense UV wavelengths and the glasses look clear again.

•  Mirrored: Layers of tint and reflective coatings combine to bounce light off the surface, reducing the amount of light that gets into your eyes. Reduces glare and eye strain but can scratch easily.

•  Gradient: Gradual shift in tint strength from top to bottom, reducing glare from the sky while retaining transparency and visibility below. Especially useful for driving, but not great outside as the lower portion generally lacks UV protection.

Regulations & Standards:

•  Ensure your sunglasses meet ISO 12312-1 or ANSI Z80.3 standards for UV protection and impact resistance.

Choosing Sunglasses:

•  UV Protection: Always opt for 100% UV protection.

•  Fit and Comfort: Ensure they fit well and are comfortable for extended wear.

•  Price vs. Quality: Higher price doesn’t always mean better protection. Focus on UV protection and lens quality over brand names.

Your eyes are so precious. Take care of them so they can take care of you.


Darkness – music to your ears

Your body clock evolved to optimise performance at different times of the day and night, with sensitivity thresholds for light adapted to cope with the 10,000-fold difference between daylight and moonlight – Diurnal Spectral Sensitivity of the Acute Alerting Effects of Light.

The same goes for hearing, with a marked diurnal shift in sensitivity and our ability to recover from loud noise during the day compared to night time – Circadian integration of inflammation and glucocorticoid actions: Implications for the cochleaThis fascinating new research in mice suggests that circadian disruption caused by constant exposure to light not only reduces our ears’ ability to recover after loud noise, it can increase risk of hearing loss – Constant Light Dysregulates Cochlear Circadian Clock and Exacerbates Noise-Induced Hearing Loss.

Given that hearing loss can double your risk of depression and other mental health issues, switching off could be music to your ears – Deafness & hearing loss facts.

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