Jet Lag: stepwise clock shifts before long-haul international flights

I didn’t plan to become the person who fiddles with bedtime like it’s a radio dial, but after a few bleary trips that felt like walking through wet cement, I started experimenting. Could I “nudge” my internal clock before a long-haul flight—just a little each day—so that arrival didn’t feel like a body-clock car crash? That question kept me company on a late-night walk last month, and by the time I got home I had a sketch: small, steady phase shifts, supported by timed light, caffeine with intent, and gentle meal and activity cues. I’m sharing what I’ve learned here the way I’d write it in my own journal—curious, honest, and careful not to promise magic. The gist: gradual changes matter, and they matter more when you pair them with light at the right time. For a plain-language primer on what jet lag actually is, the CDC has a simple overview you can skim while you sip coffee, and it’s a good grounding point to start from—see the CDC on jet lag.

Why nudging your clock beats toughing it out

There’s a stubborn myth that jet lag is just “part of travel” and you have to white-knuckle it. I used to think the same, until I noticed how much better I felt after even a minimal preflight shift. The biology is straightforward: our circadian system likes consistency, using light and behavior cues (sleep, meals, movement) to keep time. A sudden 6–12 hour jump overwhelms those signals. A slower ramp gives your clock something it can actually follow. In other words, don’t yank it—guide it. If you want a deeper clinical angle, the American Academy of Sleep Medicine has a patient-friendly explainer that maps the core ideas without the jargon: AASM Jet Lag disorder.

  • High-value takeaway: start shifts 3–5 days before takeoff when possible; 60–90 minutes earlier per day for eastbound, 60–90 minutes later for westbound can be enough to feel the difference.
  • Pair sleep-time changes with timed light exposure and dimming—light is the strongest clock cue we have.
  • Keep expectations human. Individual response varies with age, chronotype (morningness/eveningness), and how many time zones you cross.

Eastbound and westbound call for different moves

Eastbound trips generally require a phase advance (sleep earlier, wake earlier). Westbound asks for a phase delay (sleep later, wake later). That’s the foundation for your plan. I like to write two mini playbooks—one for each direction—so I don’t improvise at 1 a.m. the week before departure.

  • Eastbound example: New York to Paris (~6 hours ahead). Bedtime pushes earlier by ~1 hour per day starting four days before. Morning light exposure soon after waking; avoid bright light late evening.
  • Westbound example: Boston to Tokyo (~13 hours ahead, effectively 11 hours west with the date line). Bedtime shifts later by ~1–1.5 hours per day; get bright light in the evening; keep mornings dim.
  • Edge cases: Trips of 2–3 days may not be worth a full pre-adaptation—partial shifts and smart light timing may be kinder than a total reset.

For plain-language background on circadian timing and health in general, I find MedlinePlus pages useful as a first stop: MedlinePlus on circadian rhythm. Pair that with a travel-health angle from the CDC or your country’s public health site, and you’ve got a balanced baseline.

A gentle, stepwise preflight plan I actually use

Here’s the flexible template I keep taped to my fridge. It assumes a departure on a Friday evening; change “days” to match your schedule. Adjust the magnitude if you’re crossing fewer time zones.

  • Day −5 and −4: Nudge sleep by ~60 minutes in the target direction. Match wake time too—don’t just shift bedtime. Do a brief walk outside after your new wake time if weather allows.
  • Day −3 and −2: Add another ~60 minutes. Nudge meal times in the same direction (breakfast, lunch, dinner each about an hour earlier for eastbound, later for westbound). Keep evening screens dim or use night-shift settings.
  • Day −1 (travel eve): Do your last nudge. Pre-pack your first 24 hours abroad so you’re not decision-fatigued when you land.
  • Flight day: Use the plane as a moving dimmer switch. If you’re “pretending” it’s nighttime at your destination, eye mask and quiet. If you need alertness, brief movement and hydration beat another soda.
  • Arrival day: Anchor to the destination clock. Seek light at the biologically right time (more on that below), keep naps brief (20–30 minutes), and eat on local schedule even if portions are small.

None of this needs to be perfect. It’s the trend that counts. Even two preflight shifts can soften the landing in your body.

Light timing is the secret lever

Light can advance or delay your clock depending on when you get it. That’s why two travelers can have the same coffee, the same seat, and very different jet lag outcomes—one sought morning light when it helps, the other soaked in bright light at the worst possible time. The classic “phase response” idea says: for eastbound trips, chase morning light and avoid bright late-night light; for westbound, do the reverse. The AASM’s patient guide echoes this and translates it into simple actions: AASM basics on light timing.

  • Morning light for eastbound: Step outside within 30–60 minutes of your advanced wake time. Even a cloudy morning can help.
  • Evening light for westbound: Keep lights brighter after your delayed dinner, then dim progressively.
  • Protect the flip side: Sunglasses and a cap aren’t just style—they’re tools to avoid mistimed light.

If you like structured checklists, the NIH has general circadian rhythm resources you can bookmark: NIH circadian overview. I glance at it whenever I forget the “why” behind the routine.

Food, movement, and caffeine as small helpers

I treat these as “supporting actors,” not the star. They’re useful, but they can’t overpower badly timed light.

  • Meals: Eat on the schedule you’re aiming for during preflight days. I downshift dinner size a bit when advancing for eastbound—it makes an earlier bedtime less fidgety.
  • Movement: Short bouts—10 to 20 minutes—around your new wake time help signal “daytime” to your brain. I avoid intense late-night workouts during eastbound prep; they wake me up.
  • Caffeine: Use it like a highlighter, not a paint bucket. Time it early in the “new” day; skip it in the “new” evening. The CDC’s travel-health page on jet lag echoes the idea of timing, not just total dose: CDC jet lag tips.

Where melatonin and sleep medicines fit and don’t fit

This part gets a lot of airtime, so I’ll share how I think about it—not a prescription. Melatonin is a hormone your body makes; in supplement form, research suggests it can help with jet lag when timed properly. Doses in studies vary widely; many trials use low-to-moderate amounts and target the destination bedtime. A well-known synthesis of the evidence concluded melatonin is likely helpful for eastbound and long westbound trips when taken close to the intended local bedtime; what matters most is timing rather than a “mega dose.” If you’re curious, the Cochrane review is a good place to see how these trials were designed: Cochrane on melatonin for jet lag.

  • Talk to a clinician first if you’re pregnant, nursing, have seizure disorders, mood disorders, autoimmune conditions, or take anticoagulants or sedatives.
  • Prescription sleep medicines may shorten sleep onset, but they don’t reset your body clock. If used, it should be short-term and carefully supervised; next-day drowsiness and falls are real risks.
  • “Natural” doesn’t mean benign. Melatonin content can vary across brands; look for third-party testing and avoid mixing with alcohol.

Putting it together for real itineraries

These are the pencil-and-paper mini plans I actually used this year. They’re examples, not rules. I keep them messy on purpose; a plan you’ll follow beats a perfect plan you won’t.

  • NYC → London (5 hours east), Monday morning arrival: Wed: bed 11:30 p.m. → 10:30; Thu: 10:30 → 9:30; Fri: 9:30 → 8:30; Sat: maintain. Morning outside light after waking; last caffeine by 2 p.m. local during prep days. Plane: if it’s “night” in London, eye mask and quiet. Arrival: morning light walk, nap max 20 minutes, early modest dinner, lights out on London time.
  • LA → Seoul (16 hours ahead, effectively 8 hours west): Start Sat: push bedtime later by ~1 hour nightly for four nights; get evening bright light outside or with room lights; keep mornings dim with sunglasses if you head out early. On arrival, seek light mid-to-late afternoon local, not early morning.
  • Short trip edge case, 2 nights only: Minimize flip-flopping. Keep partial home schedule, prioritize functional alert windows (meetings) with timed light and caffeine, and don’t chase perfection.

Little habits I’m testing and keeping

Some things worked so consistently for me that they’ve become non-negotiables.

  • “Light budget” checklist: I list the two hours I most need to protect from bright light and the two hours I most want it. Sunglasses live in my carry-on.
  • Meal anchors: I print—or at least sketch—my target mealtimes for the first 48 hours abroad and circle the first breakfast, lunch, and dinner on local time.
  • Micro-mobility: Ten-minute stretch or walk every 3–4 hours during the first day. It keeps the “I’m stuck in molasses” feeling from spiraling.

For broader patient-facing travel advice that avoids hype yet stays practical, I like to skim medical organization pages before a complex trip. The AASM patient page I linked above stays close to evidence without losing empathy; MedlinePlus keeps the language plain and useful; and the CDC’s travel notes are a nice safety net for reminders I forget.

Signals that tell me to slow down and double-check

I watch for patterns that suggest I’ve pushed too hard or missed the timing window. It’s not about alarm—it’s about course-correcting early.

  • Red flags: severe or escalating insomnia, excessive daytime sleepiness that affects safety (e.g., driving), chest pain, shortness of breath, syncope, or new neurologic symptoms. These are not “just jet lag.” Get medical help promptly (urgent care or emergency services as needed).
  • Amber flags: mood swings beyond your usual, persistent GI upset, or headaches that don’t respond to your typical self-care. Time your light more carefully; trim caffeine late day; consider asking a clinician about short-term aids.
  • Preference-sensitive choices: timing of workouts, breakfast size, whether to use a low-dose melatonin supplement. These can be adjusted based on your priorities and how you feel.
  • Keep records: I jot down bedtime, wake time, when I got light, and how I felt on a 1–5 scale. Three lines per day is enough to guide adjustments.

When in doubt, a reputable education page can help you sort “need-to-know now” from “nice-to-know later.” MedlinePlus has a straightforward jet lag page: MedlinePlus Jet Lag.

What I’m keeping and what I’m letting go

After a half-dozen long hauls this year, I’m keeping three principles: start early, respect light, and anchor with simple routines. I’m letting go of the idea that I can out-stubborn biology by “powering through.” Instead, I’ll keep my stepwise shifts (even two nights helps), protect light timing like it’s medicine, and be generous with myself when the plan goes sideways. If you want a single source to reread before your next trip, bookmark the CDC page I linked earlier for practical guardrails, and the AASM page for a clock-savvy view of timing. When you’re curious about the supplement angle, skim the Cochrane review to see how researchers tested melatonin and what caveats they found.

FAQ

1) Should I always shift before every long-haul flight?
Answer: Not always. If you’re crossing 5+ time zones and staying at least 3–4 days, preflight shifts help most. For very short trips, partial adaptation and smart light timing may be kinder than a full reset. The CDC overview echoes the “timing matters” principle.

2) How many hours per day can I shift safely?
Answer: Many people tolerate ~60–90 minutes per day. Sensitive sleepers or those with rigid schedules might prefer smaller steps. If you have sleep disorders or complex medications, personalize with a clinician’s input; the AASM patient guide explains the logic.

3) Is melatonin necessary?
Answer: No, it’s optional. Evidence suggests it can help when timed to destination bedtime, especially for eastbound trips. Quality and dosing vary, and it’s not right for everyone. Review the Cochrane review and check with a clinician if you have conditions or take interacting meds.

4) Do blue-light–blocking glasses work?
Answer: They can reduce evening light exposure, which helps for eastbound advances. The key is consistency: wear them when you’d otherwise be soaking in bright screens or indoor lighting in your “new” evening.

5) What about kids or older adults?
Answer: The same principles apply—gentle shifts and light timing—but the pace may need to be slower, and supplements should be discussed with a pediatrician or clinician. Simple anchors (meals, morning sunlight, short walks) are usually the safest first steps.

Sources & References

This blog is a personal journal and for general information only. It is not a substitute for professional medical advice, diagnosis, or treatment, and it does not create a doctor–patient relationship. Always seek the advice of a licensed clinician for questions about your health. If you may be experiencing an emergency, call your local emergency number immediately (e.g., 911 [US], 119).