Blue Light
No piece of sleep advice has been repeated more than "stop looking at screens before bed". It is also the piece most often explained wrongly — including, we should admit, by companies that sell blue light glasses.
Here is the honest version, including the parts that don't flatter us.
What light actually does
Your eyes contain a set of cells that have nothing to do with vision. Discovered in the late 1990s and studied in depth by Russell Foster's group at Oxford, they contain a pigment called melanopsin, and their job is to tell your brain how bright the world is.
They are most sensitive to light in the blue part of the spectrum — around 480 nanometres — which is where "blue light" entered the conversation. When they fire, the message is unambiguous: it is daytime. Melatonin release is suppressed, and the internal clock is nudged later.
Melatonin is not a sedative. It is an announcement that night has begun. Light at night doesn't keep you awake by stimulating you — it delays the announcement, so you get into bed on schedule and your body starts winding down twenty or forty minutes late.
The part everyone leaves out
The villain is not the colour. It is the intensity, the timing, and how much of your visual field the light fills.
A phone at arm's length delivers a modest amount of light to your eyes. A ceiling light fills your entire field of view for hours. In many homes the overhead lighting is doing considerably more circadian damage than the phone everyone feels guilty about — it just doesn't come with a screen time notification at the end of the week.
If you fix your ceiling light and change nothing else, you have probably done more than any pair of glasses will do for you.Our honest position
So do blue light glasses work?
We sell them, so read this with that in mind.
They do what they claim mechanically: amber-tinted lenses filter part of the short-wavelength light before it reaches your eye. Reducing the dose is real.
What the evidence does not support is the bigger promise. The research on whether wearing them meaningfully improves sleep is mixed, the studies are often small, and effects are modest. Anyone quoting you a dramatic percentage is quoting something you should ask to see.
Where we think they genuinely earn their place
- When you cannot avoid screens late — shift work, a deadline, a time zone that isn't yours
- As a cue. Putting glasses on at half past nine is a physical marker that the evening has changed gear. That behavioural effect may matter as much as the optics.
Where they don't
- As a substitute for dimming the room. Glasses filter what reaches your eyes; they don't fix a bright house.
- As a licence to scroll until 1am. The content is stimulating regardless of its colour temperature — a device engineered to keep offering you one more thing is a poor companion for an activity requiring you to stop wanting things.
What we would do first, in order
- Turn off the overhead light an hour before bed. Free, and the biggest single change.
- Move light lower and warmer. Two lamps beat one ceiling fitting. Warm bulbs beat daylight bulbs.
- Turn on night mode on your devices. It costs nothing and reduces the dose.
- Protect the final twenty minutes. If you won't give up the evening scroll, give up its last stretch. Proximity to sleep is what counts.
- Then, if screens are unavoidable late, add glasses.
Because a customer who buys glasses expecting to fall asleep in five minutes will be disappointed, and rightly. We would rather sell you one honest thing than three that overpromise — and if the honest answer for you is a dimmer switch rather than a purchase, that is a good outcome for us too.