“Blue Light Isn’t the Villain We Once Thought”
By Dr Amanda Gamble, Clinical Sleep Psychologist
For years, blue light has been blamed for wrecking our sleep. If you’ve ever been told to “avoid screens for two hours before bed or you’ll destroy your melatonin,” you’ve heard the extreme version of this message.
But here’s the truth:
The science has shifted — and it’s far more nuanced than the headlines suggest.
As the lead author of one of Australia’s largest surveys on teen sleep and technology use, and in reviewing the research that followed, it’s clear that blue light is not the sole culprit behind sleep problems. In fact, in many cases, it’s not even the most important factor.
Let’s break down what we actually know.
1. Yes, some blue light suppresses melatonin — but the real-world impact is often much smaller than people think
Laboratory studies show that exposure to short-wavelength (blue) light can suppress melatonin production. That part is true.
But what’s also true — and much less well-known — is this:
Melatonin suppression does not automatically delay sleep onset in every individual.
Many people still fall asleep at their normal time, even with moderate evening screen use.
Why?
Because sleep is influenced by a complex mix of:
circadian rhythm timing
sleep pressure (homeostatic drive)
stress levels
emotional arousal
behavioural patterns
timing and type of technology use
Blue light is only one small piece of the puzzle.
2. Our research: device type and activity matter more than blue light alone
In the study we published — The ABC Big Sleep Survey (Gamble et al., 2014) — we examined the sleep patterns and technology habits of over 1,100 adolescents across Australia.
Our findings surprised even us.
Not all devices affect sleep equally.
Some key results:
Passive devices (audio and TV) had the smallest impact on sleep timing.
Interactive devices (phones, computers, gaming) had the largest impact — regardless of blue light output.
Device use showed a dose-response relationship — meaning frequency and intensity mattered. Occassional use had virtually no impact, whilst using a device “almost every night” impacted sleep.
This points toward a behavioural and neurological explanation, not simply a light-based one.
3. The real disruptor: cognitive and emotional arousal
Here’s what updated research consistently shows:
Interactive, stimulating screen use is far more disruptive to sleep than blue light itself.
Examples:
scrolling through social media
texting or messaging
gaming
creating content
waiting for likes or replies
high-engagement apps designed to keep you hooked
watching fast-paced or emotionally activating content
These activities activate the reward system, increase dopamine, raise cognitive load, and keep the brain in an alert, “switched on” state.
This is neurobiologically incompatible with winding down for sleep.
In contrast:
Passive viewing (e.g., TV across the room)
produces far less blue light exposure
generates less cognitive arousal
often has minimal impact on sleep onset
is well-tolerated by many individuals
This is why watching TV before bed doesn’t delay sleep for most people.
4. So… should we avoid screens before bed? Not exactly.
The old advice (“no screens two hours before sleep!”) was based on early melatonin-suppression studies and has not held up well in real-world research. A more balanced, evidence-based approach is:
✔ Reduce stimulating, interactive screen activities in the hour before bed (scrolls, chats, games, work emails, competitive content)
✔ Passive viewing is generally okay (TV across the room, relaxing content)
✔ Dim the screen and use Night Shift/Blue Light filters (not perfect, but they help reduce alerting effects in some individuals)
✔ Choose soothing content (gentle shows, music, podcasts, audiobooks)
✔ Prioritise emotional wind-down (reading, stretching, showering, breathing exercises)
✔ Keep screens out of the bed itself (screen use in bed is strongly linked with delayed sleep)
This approach respects both the science and real life.
5. The bottom line: screens aren’t the enemy — overstimulation is.
The narrative around blue light was oversimplified.
A more accurate summary is:
🟦 Blue light can suppress melatonin,
but doesn’t reliably stop people from falling asleep.
🟦 Device type matters — not all screens are equal.
Interactive devices tend to be the most sleep-disruptive.
🟦 It’s time to move past fear-based messaging.
A nuanced, realistic approach better supports teens, adults, and families.
If sleep is still difficult… support is available
If you or your child is struggling with sleep — whether it’s insomnia, delayed sleep phase, night-time fears, or device-related habits — personalised, evidence-based support can make a significant difference.
