Dr Rangan Chatterjee Explains How Light Can Help You Sleep Better
Rebecca Miller
When most people think about improving their sleep, they tend to focus on caffeine and alcohol consumption or simply trying to sleep for longer.
But for Dr Rangan Chatterjee, a member of The BON CHARGE Scientific Advisory Board, one of the biggest influences on how well we sleep is something many might not even consider: light.
"When people think about sleep, they naturally go to things like caffeine and alcohol," he says. "I don't think people think about light enough."
It's a simple observation, but one that reflects a broader shift in how we understand sleep.
Rather than beginning the moment we get into bed, sleep is influenced by the signals our body receives throughout the entire day.
Light is one of the strongest regulators of our circadian rhythm - the internal body clock that helps determine when we feel alert and when we feel sleepy, with research showing that both morning and evening light exposure can influence circadian timing, sleep and mood.1
Your sleep starts long before bedtime
For Dr Chatterjee, the conversation around sleep starts first thing in the morning.
"There is growing awareness that exposing ourselves to natural light in the morning is important to set and almost ground our circadian rhythm," he explains.
Morning daylight acts as an important cue for the body's internal clock, helping synchronise it with the natural day-night cycle.1
Even spending a short time outdoors soon after waking can help reinforce this natural rhythm.
Why evenings can leave us feeling wide awake
Phones, laptops, TVs and bright household lighting have transformed the modern evening, often extending daytime long after the sun has set.
(Photo by iStock of a couple watching TV in the evening)
The screens and LED lights we surround ourselves with emit blue-rich light, which helps keep us alert during the day but can also influence circadian timing and melatonin signalling when we're exposed to it late into the evening.
Research has shown that evening blue light can affect circadian timing and sleep, although the extent of these effects varies between individuals.2,3
Dr Chatterjee believes the challenge isn't a lack of awareness, but the realities of modern life. Most people already know that screens can affect sleep, yet disconnecting completely in the evening often isn't realistic.
"People are aware of blue light exposure at night, but smartphones are so addictive that most people don’t do anything with that information," he says.
In his clinical experience and personal observations, Dr Chatterjee has found that people don't all respond to evening light in the same way.
"Some people are more sensitive than others. For some people it is literally game changing."
That has certainly been true in his own experience.
"I noticed that if I could wear some blue light blocking glasses for an hour before bed, I would just naturally feel more sleepy.”
“A lot of people don't realise that the reason they don't feel tired until later is because of the light they're exposing themselves to."
Rather than expecting people to eliminate screens altogether, Dr Chatterjee believes it's more realistic to focus on reducing their impact.
Forget perfection, focus on what's realistic.
One of the strongest themes running through Dr Chatterjee's approach to life is practicality.
"There's optimal and then there's what's realistic," he says. "Anything we can do makes a difference."
In an ideal world, he suggests people would spend the last hour or more before bed away from screens, under dim lighting and doing relaxing activities. But he is also realistic about how modern life works.
(Photo of BON CHARGE's Low Blue Light Bulb to help create a dimly lit room)
He explains: "For some people, they're going to go, 'No chance.’”
Rather than abandoning the idea altogether, he encourages people to make changes that feel achievable.
Even reducing screen exposure for 30 minutes - or sometimes just 15 minutes - before bed can make a noticeable difference for some people.
This idea aligns with emerging circadian research, which suggests that reducing evening light exposure may support healthier sleep patterns, even if perfect routines aren't always possible.1,2
If screens are unavoidable, reduce their impact
For many people, avoiding screens altogether simply isn't practical. Work, family and everyday communication often continue into the evening.
Instead of insisting people disconnect completely, Dr Chatterjee recommends reducing the impact wherever possible.
He suggests:
- Lowering screen brightness.
- Using warmer or red display settings if available.
- Wearing Blue Light Blocking Glasses when evening screen use can’t be avoided.
Blue light blocking glasses have been investigated as one way of reducing evening blue-light exposure, with systematic reviews suggesting they may benefit sleep or circadian-related outcomes for some people, although results remain mixed.4
He also believes it's worth paying attention to how we use our devices before bed.
"If you're sending stressful work emails in bed and then wondering why you can't fall asleep, it's probably because of how stimulated you are,” he says.
Instead, he recommends choosing content that feels relaxing or uplifting as the day comes to an end.
Why sleep affects so much more than sleep
Dr Chatterjee describes sleep as one of his four pillars of health, alongside food, movement and relaxation.
"They're all important. And all of them impact the others," he says. "But for many people... sleep may well be the foundational pillar."
(Photo by Clare Winfield of Dr Rangan Chatterjee)
He explains good sleep doesn't simply leave us feeling more rested, it often changes how we experience the following day.
"Your mood is better. You're less anxious. You're more emotionally regulated. You're more able to resist temptation. You're more creative. You eat less,” he adds.
He also points to research showing that adults sleeping around five and a half hours a night consumed roughly 300 more calories the following day than those sleeping eight hours, highlighting how sleep can influence appetite through changes in hunger and satiety hormones.
More broadly, research supports many of these connections.
Sleep restriction has been shown to influence appetite and food intake in the short term, while long-term poor sleep has been associated with an increased risk of several chronic health conditions.1
Building healthy habits into everyday life
Rather than asking people to create entirely new evening routines, Dr Chatterjee prefers habits that naturally fit into the ones they already have.
He uses his own evening wind-down routine as an example.
"I do 10 minutes of stretching with my BON CHARGE Demi Red Light Therapy Device on," he says. "I do that stretching anyway. I don't have to create extra time in my day. It's one of the ways I like to wind down and look after my body and mobility as I get older."
(Photo of the BON CHARGE Demi Red Light Therapy Device that Dr Rangan Chatterjee uses)
For Dr Chatterjee, the appeal is that the red light panel simply becomes part of a routine he already enjoys, rather than another health habit to find time for.
Research into red light therapy is continuing to evolve, with some studies reporting improvements in sleep quality following red light exposure, although further research is needed to better understand its role.5
Whether it's stretching, mobility work or another calming activity, his broader message is that healthy evening habits are more likely to stick when they fit naturally into everyday life. Consistent, relaxing routines before bed can help signal to the body that it's time to transition towards sleep.1
"Anything that we can do to help us live in harmony with the way that we used to live is going to be a good thing," he says.
As modern life becomes increasingly connected and screen-based, Dr Chatterjee believes practical tools that work alongside existing habits may help people reduce some of the challenges that come with living in that environment.
Read More: Meet The BON CHARGE Scientific Advisory Board members
Small changes can make a meaningful difference
Dr Chatterjee's approach to sleep isn't built around chasing perfection.
Instead, it centres on recognising that modern life isn't likely to become less busy or less digital any time soon - and making realistic adjustments that fit within it.
Morning daylight, dimming screens, choosing relaxing activities before bed - finding simple habits that become part of an existing routine.
"There's optimal and then there's what's realistic," he says.
For many people, that may be the most practical place to start if you want to improve your sleep.
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References
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Blume, C., Garbazza, C. & Spitschan, M. Effects of light on human circadian rhythms, sleep and mood. Somnologie 23, 147–156 (2019).
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Wahl, S. et al. The inner clock—Blue light sets the human rhythm. J. Biophotonics 12, e201900102 (2019).
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Silvani, M. I., Werder, R. & Perret, C. The influence of blue light on sleep, performance and wellbeing in young adults: A systematic review. Front. Physiol. 13, 943108 (2022).
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Hester, L. et al. Evening wear of blue-blocking glasses for sleep and mood disorders: A systematic review. Chronobiol. Int. 38, 1375–1383 (2021).
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Zhao, J. et al. Red light and the sleep quality and endurance performance of Chinese female basketball players. J. Athl. Train. 47, 673–678 (2012).
BON CHARGE: This content is for general education and is not medical advice. Our products are not intended to diagnose, treat, cure, or prevent any disease. Always follow product instructions and consult a qualified healthcare professional for guidance tailored to you. Individual results may vary.
