Ra Optics vs Swanwick vs TrueDark vs Bon Charge, tested for blue transmission percentage at specific wavelengths.
Questions logged on this protocol
Do blue-blockers actually preserve melatonin?
The red-tint evening lenses, yes. Burkhart & Phelps 2009 (Chronobiol Int) and Shechter et al. 2018 (J Psychiatr Res) showed amber/red blue-blockers worn 2-3 hours before bedtime preserved dim-light melatonin onset relative to controls. Effect sizes are meaningful for evening screen users. Clear and light-yellow 'computer glasses' show minimal circadian effect; they are eye-comfort products, not circadian products.
What wavelength do they need to block?
Melanopsin, the circadian photoreceptor, peaks at ~480 nm, with the functional range ~440-500 nm. A genuine evening lens should block nearly all transmission below ~500 nm, ideally below ~550 nm. The red-amber appearance is diagnostic: a clear or light yellow lens is not doing enough.
When should I put them on?
2-3 hours before target bedtime. Cajochen et al. 2011 (J Appl Physiol) showed evening light suppresses melatonin within ~30 minutes of exposure, so the window to prevent that suppression is the pre-DLMO period. For a 23:00 bedtime, that means 20:00-21:00 put-on time. Keep them on until you turn the lights off.
Can I just use a phone night mode?
Partially. iOS Night Shift and Android equivalent warm the display color temperature, reducing blue output from the screen. They do nothing for overhead lights, which typically contribute more photon flux than the phone. Night mode is a useful layer; it does not replace ambient light hygiene or blue-blockers if you are in a bright-lit room.
Do they make you feel sleepy?
Not directly. They prevent melatonin suppression, which preserves the natural buildup of sleep pressure in the evening. Many users describe 'feeling sleepier at night' after a few weeks; that is the absence of iatrogenic alertness, not a sedative effect. If you feel acutely drowsy when you put them on, check for a room that is actually dimmer than you realized.
Can I wear them while working at night shift?
Generally no. Night-shift workers need alertness during shift. Smith & Eastman 2008 (Sleep Med Clin) recommend blue-blockers on the commute home (to block morning light that would otherwise prevent daytime sleep) rather than during the shift. Use them as a one-way valve into the daytime sleep window, not during active work.
- [01]
- [02]
- [03]
- [04]
- [05]
Other stacks in this hub
Best Light Therapy Lamps 2026: Dose
Light therapy lamps ranked by measured lux at 12, 18, and 24 inch distances, not marketing claims. With $/measured-lux.
Best Sunrise Alarm Clocks 2026
Sunrise alarms ranked by max lux at pillow distance and sunrise duration. Those are the two metrics that actually map to a wake-time phase shift.
Magnesium Glycinate for Sleep: Protocol, Dose, Evidence
Lab-notebook protocol for magnesium glycinate as a sleep aid. The 200–400 mg evening dose, the Abbasi 2012 RCT, the glycinate-vs-citrate question, and the failure modes nobody surfaces.