It Depends: Flying East or West? How to Use Blue Light-Blocking Glasses to Beat Jet Lag

If you've ever landed in a distant city only to feel like your body is still somewhere over the Atlantic, you've experienced one of biology's most stubborn challenges. Jet lag isn't just fatigue - it's a biological mismatch between your circadian clock and the external world around you.[1]

But here's the empowering part: you have more control over this process than you might think. One of your most powerful tools? Blue light-blocking glasses, worn with strategic foresight.

Inside Your Body's Timekeeping System

Deep in your brain, nestled within a region called the hypothalamus, sits a tiny cluster of neurons known as the suprachiasmatic nucleus (SCN) - your body's master clock.[1] This remarkable structure orchestrates a 24-hour rhythm that governs everything from your hormone release to your body temperature, from your alertness to your hunger.

When you fly across time zones, something fascinating and frustrating happens: your internal clock keeps ticking to the rhythm of your departure city, while the sun, the meal times, and the social schedules around you operate on an entirely different schedule. Your body doesn't simply flip a switch. Instead, it adjusts slowly - roughly half a day for each time zone when you travel westward, but a full day per time zone when you head eastward.[1]

That transatlantic flight from New York to London? Without intervention, your body may take five to six days to fully synchronize with local time.

How Light Writes the Rules of Your Internal Clock

Light is the most powerful signal your body uses to set its circadian rhythm.[1] But not all light affects you equally.

Inside your eyes, you have specialized cells called intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells contain a light-sensitive protein called melanopsin, which responds most strongly to light in the blue-green range - specifically, wavelengths around 464 nanometers.[2] When melanopsin detects this blue-enriched light, it sends a direct signal to your SCN, essentially announcing: "It's daytime. Stay alert. Suppress melatonin."

This system evolved to keep us synchronized with the sun. But in our modern world, artificial light - from your phone screen, your laptop, cabin lighting on overnight flights - floods your eyes with these same blue wavelengths long after the sun has set. The result? Your brain receives conflicting messages, and your circadian phase shifts later, making it harder to fall asleep when you need to.

Blue light blocking glasses filter out wavelengths in the 400-550 nanometer range, effectively creating an artificial sunset for your brain. Even when you're surrounded by bright artificial light, your melanopsin system registers darkness.

A systematic review examining 29 studies with 453 patients found that wearing these glasses in the evening substantially reduces the time it takes to fall asleep and helps melatonin production begin earlier.[2]

You're manually overriding the environmental light signals that would otherwise keep you awake.

Strategic Timing: Direction Matters

The key to using blue light blocking glasses effectively lies in understanding which direction you're traveling, and what your circadian system needs to do to adapt biologically.

When You Fly East: Advancing Your Clock

Eastward travel - say, from Los Angeles to London - requires your body to shift forward in time. You need to sleep earlier and wake earlier than your body currently wants to. This is particularly challenging because your natural circadian rhythm tends to run slightly longer than 24 hours, making it easier to stay up late than to go to bed early.

Your approach:

• During overnight flights: Wear blue blockers during the latter portion of the flight to help facilitate sleep
• Morning at destination: Do NOT wear blue blockers. Instead, seek bright morning light—this is what advances your clock forward
• Evening at destination: Wear your glasses 2-3 hours before your destination bedtime.[2] Evening light would otherwise delay your already-late circadian phase.

Duration: Continue wearing them nightly until you've adapted—roughly one day per time zone crossed.

When You Fly West: Delaying Your Clock

Westward travel - from London to Los Angeles, for instance - requires the opposite adjustment. Your body needs to delay its rhythm, staying awake and sleeping later than it naturally wants to.

Your approach:

• Early morning at destination: If you arrive very early in the morning, wear blue blockers to prevent morning light from advancing your clock when you actually need it to delay.
• Afternoon and evening: Stay awake and seek light exposure - this helps delay your circadian phase.
• During flight: Generally, avoid wearing blue blockers so you can align more naturally with the later schedule at your destination.

Remember: Blue light is everywhere: not just your phone or laptop, but also your TV, overhead lights, even the glow from your refrigerator. For maximum effect, wear your glasses throughout the evening until sleep, not just during screen time.

Combining Strategies: The Power of Multiple Signals

Your circadian system responds to more than just light. When you combine multiple interventions, the synergy becomes powerful:[1]

Strategic light exposure remains your primary tool. Morning light advances your circadian clock, helping you sleep and wake earlier. Evening light delays it, helping you sleep and wake later. Natural sunlight is the most effective synchronizer, so get outside at your destination.

Meal timing matters more than you might expect. Your peripheral clocks - the ones in your liver, gut, and other organs - respond strongly to when you eat. Align your meals with destination time zones, even if you're not particularly hungry at first.

Exercise timing provides another lever for adjustment. Physical activity resets both your central clock and your peripheral clocks throughout your body. Early evening exercise tends to advance your phase, helping you sleep earlier. Late-night exercise delays it, helping you sleep later. Morning chronotypes may benefit especially from light to moderate morning exercise.

These signals work together, each reinforcing the others, creating a coherent message to your body about what time it is.

What This Means for You

When used strategically, blue light blocking glasses are a scientifically validated tool for recalibrating your circadian rhythm. The research is robust: blue light blocking glasses are particularly effective at reducing sleep onset latency (the time it takes to fall asleep) in patients with sleep disorders, jet lag, or variable shift work schedules.[2]

This isn't about fighting your biology - it's about working with it. Your circadian system is remarkably adaptive when you send it the right signals at the right times. Blue light blocking glasses give you that control, transforming artificial light from a disruptor into something you can manage.

Travel well, sleep deeply, and let your body find its rhythm again.

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.

References

1. Ahmed, O., Ibrahiam, A.T., Al-Qassab, Z.M., Kannan, V., Ullah, N., Geddada, S. & Nassar, S.T. Unraveling the impact of travel on circadian rhythm and crafting optimal management approaches: a systematic review. Cureus 16, e71316 (2024).
2. Hester, L., Dang, D., Barker, C.J., Heath, M., Mesiya, S., Tienabeso, T. & Watson, K. Evening wear of blue-blocking glasses for sleep and mood disorders: a systematic review. Chronobiol. Int. 38, 1375–1383 (2021).