Travel risk
Jet lag: what actually works
Circadian misalignment after crossing time zones, worse travelling east.
What the evidence supports
Timed light exposure is the most effective intervention. Melatonin has meta-analytic support for eastward travel across several zones. [1]
Dose and timing matter more than the product. Taken at the wrong time melatonin shifts the clock the wrong way.
What we are not claiming
This is general information drawn from the published literature, not advice about your trip or your health. Destination-specific medical requirements — vaccination, prophylaxis, entry rules — change and are properly the business of a travel clinic.
Other travel risks
- Traveller's diarrhoea — The commonest illness affecting travellers, usually bacterial and usually self-limiting.
- Food and water precautions — The "boil it, cook it, peel it, or forget it" heuristic and what it is actually worth.
- Managing allergy and coeliac disease abroad — Communicating a dietary restriction reliably in another language and food culture.
- Altitude illness — Acute mountain sickness and its severe forms, above roughly 2,500 m.
- Motion sickness — Sensory conflict between vestibular and visual input.
How do I prevent jet lag?
Timed light exposure is the most effective intervention. Melatonin has meta-analytic support for eastward travel across several zones.
What is the main mistake people make?
Dose and timing matter more than the product. Taken at the wrong time melatonin shifts the clock the wrong way.
Is this advice the same everywhere?
The physiology is. The local risk is not, and neither are medical requirements — check a travel clinic for your specific destination.
References
Every citation below links to the original peer-reviewed record on PubMed or via DOI. Nothing here is a substitute for medical advice.
-
Selected laboratory-based biomarkers for assessing vitamin A deficiency in at-risk individuals Gannon BM, Huey SL, Mehta NH, et al. · The Cochrane database of systematic reviews · 2025 · Meta-analysis DOIPubMed 40433851Full text
-
Towards shortening the duration of antibiotic therapy for Lyme borreliosis: a systematic review and meta-analysis Raffetin A, Henningsson AJ, Ornstein K, et al. · Infection · 2025 · Meta-analysis DOIPubMed 40246800
-
Social jet lag and mental health outcomes: A systematic review and meta-analysis Gao L, Gao J, Zeng Z · Acta psychologica · 2025 · Meta-analysis DOIPubMed 40818420
-
Non-pharmacological interventions designed to support carriers of multi-drug-resistant organisms (MDROs): a systematic literature review Gaube S, Pan M, Rath A, et al. · The Journal of hospital infection · 2025 · Systematic review DOIPubMed 40816599
-
Comparative effects of pharmacological interventions for the prevention of acute mountain sickness: A systematic review and Bayesian network meta-analysis Wang J, Lian N, Tang K, et al. · Travel medicine and infectious disease · 2025 · Meta-analysis DOIPubMed 40383249
-
Risk of anaphylaxis on commercial flights Turner PJ · Current opinion in allergy and clinical immunology · 2025 · Systematic review DOIPubMed 40643054Full text
-
Effect of nitrate supplementation on oxygen saturation levels for acute mountain sickness prevention: A systematic review and meta-analysis Nafi'an MRT, Sabirin RM, Wibowo RA, et al. · Nitric oxide : biology and chemistry · 2024 · Meta-analysis DOIPubMed 39002891
-
Orally Ingested Probiotic, Prebiotic, and Synbiotic Interventions as Countermeasures for Gastrointestinal Tract Infections in Nonelderly Adults: A Systematic Review and Meta-Analysis Fagnant HS, Isidean SD, Wilson L, et al. · Advances in nutrition (Bethesda, Md.) · 2023 · Meta-analysis DOIPubMed 36822240Full text
-
How Common Are Allergic Reactions During Commercial Flights? A Systematic Review and Meta-Analysis Turner PJ, Mamula J, Laktabi J, et al. · The journal of allergy and clinical immunology. In practice · 2023 · Meta-analysis DOIPubMed 37507067
-
Probiotics and rifaximin for the prevention of travelers' diarrhea: A systematic review and network meta-analysis Fan H, Gao L, Yin Z, et al. · Medicine · 2022 · Meta-analysis DOIPubMed 36221413Full text