The Science Behind Better Light

How much blue light the lens filters out across a stated range. InvisiAid blocks 35% between 400 and 500nm. SleepAidMax blocks 99.7% of blue and green light up to 580nm. Higher is not automatically better — daytime light is meant to reach your eyes. The right figure depends on the time of day, not on the size of the number.

How much total light passes through, which is how dark the lens looks. InvisiAid transmits 86% and reads as near-clear. Oasis transmits 14.80% and is a true sunglass. VLT decides whether a lens is comfortable indoors — and whether it is legal to drive in.

An international scale from 0 to 4, set by ISO 12312-1, describing how dark a lens is. Category 0 suits any indoor use. Category 3 is for bright sun. Our lenses span 0 to 3. Category 4 is never permitted for driving, in any conditions.

Every number on this page is measured by Micor-Light Optics against ISO 12312-1 and ANSI Z80.3. They are laboratory measurements of our actual lenses, not estimates from the tint colour or figures copied from a supplier.

A lens must transmit at least 75% of visible light to be legal to drive in at night. Nothing in our range clears that bar, which is why no lens here is sold as a night-driving lens. Treat every pair, Shade Gray included, as indoor, outdoor or passenger wear once the light goes.

Adapt is the only lens in the range certified as driving-compliant, and daytime only. Its photochromic tint moves between 57.98% and 23.76% transmission depending on light, staying within category 1 to 2. Do not drive in it after dark.

Both pass for daytime driving and both fail at night. Harmony transmits 67.56%, under the 75% minimum required after dark. Oasis transmits 14.80%, fails at night and in twilight, and does not meet AS/NZS 1067 — its Q-Blue value is 0.66 against a 0.70 requirement. We publish that failure rather than list only the standards it passes.

These are pre-sleep lenses. SleepAid transmits 48.23% and SleepAidMax 22.17%, and both remove enough of the spectrum to alter how you see colour, including brake lights and signals. They are not for driving at any hour.

Evening light suppresses melatonin, the hormone that signals to your body that it's night. That amber lenses reduce that suppression is the most solidly evidenced claim in this field, measured directly in saliva and blood, by independent groups, against clear control lenses.

A crossover trial in the Journal of Adolescent Health (2015) found blue-blocking glasses significantly reduced the melatonin suppression caused by evening screen use — though sleep itself was unchanged. In the Journal of Clinical Endocrinology & Metabolism (2005), blue-blocking goggles preserved melatonin under bright light during a simulated night shift without dulling alertness or task performance. A double-blind trial in Neurobiology of Sleep and Circadian Rhythms (2022) found full blue-blockers advanced melatonin onset by around 28 minutes against partial ones. These are small studies — 13, 19 and 60 people. Two authors of the third held shares in a blue-blocking eyewear company.

The same research team that found the 28-minute melatonin shift reported the sleep outcomes from that trial separately, in PLOS ONE (2022), and found no significant difference in total sleep time, sleep efficiency or insomnia severity.

The trial most often quoted in favour is a randomised crossover study in the Journal of Psychiatric Research (2018): amber lenses for two hours before bed improved sleep against clear placebo lenses in people with insomnia symptoms. It had fourteen participants, and most of its outcomes were self-reported. A systematic review in Chronobiology International (2021) concluded the intervention is worth recommending for insomnia and delayed sleep phase. The honest summary: a modest effect, most likely in people who already sleep badly, on small studies.

The largest review of this question is a 2023 Cochrane systematic review of 17 randomised trials and 619 participants. It concluded that blue-light filtering lenses may not reduce eye strain from computer use, that effects on sleep quality were indeterminate, and that no trial has measured macular health at all.

The American Academy of Ophthalmology does not recommend blue light-blocking glasses, on the grounds that there is no good evidence blue light damages the eye; the College of Optometrists says the same. We'd rather you read that here than find it later. It is why our claims stop at what the lens measurably does.

If filtering has an effect, it depends entirely on the lens doing what it claims — and most don't.

Clinical and Experimental Optometry (2020) modelled commercially available blue-blocking lenses and found they reduced circadian sensitivity by between 4 and 27 per cent depending on the product. A sixfold spread, across lenses all sold as the same thing. A bench study in Chronobiology International (2022) measured 50 commercial blue blockers directly and found reflective blue-tinted lenses — a very common style — block the least circadian-active light of all.

This is why we publish figures. Every Sleep ZM lens is measured by Micor-Light Optics against ISO 12312-1 and ANSI Z80.3, and the full table is above. You can check what you're buying, which on the evidence above is the part that actually varies.

Blue light glasses are not a treatment for eye disease, for migraine, or for a diagnosed sleep disorder. Nothing on this page diagnoses, treats or cures a condition. If you have persistent headaches, changes in your vision, or sleep problems that do not resolve, see an optometrist or a doctor. A tinted lens is not a substitute for that appointment.

Some trials find blue-blocking lenses reduce visual fatigue. Others find no advantage over clear lenses. Much of the retinal damage research uses light intensities far above anything a screen produces, frequently in cell cultures rather than in people. We think comfort during long screen days is a fair claim. Protection of the retina from ordinary screen use is not one we will make.

Melatonin suppression by evening light is well established, but sleep is also driven by caffeine, alcohol, stress, room temperature and what time you got up. An orange lens at ten at night will not undo a four o'clock double espresso. These lenses remove one obstacle. They do not do the rest of the work for you.

That every lens blocks what we say it blocks, measured by an independent laboratory against ISO 12312-1 and ANSI Z80.3, and published here in full including the one standard we fail. That is a narrower promise than most of this industry makes. It is also the only one we can hand you the paperwork for.