What Is Jet Lag?

What is jet lag?

Jet lag is a temporary sleep and fatigue problem that occurs when you travel quickly across multiple time zones, leaving your body's internal clock out of alignment with the local time at your destination. Your body runs on a roughly 24-hour internal rhythm, the circadian rhythm, that governs when you feel sleepy and alert, tied to the light and dark of your home time zone. When a fast flight drops you into a place that is several hours ahead or behind, your internal clock still thinks it is home time, so you may feel wide awake in the middle of the local night or exhausted during the local day. Jet lag is this mismatch, and it is a normal, if unpleasant, part of long-distance air travel.

What causes jet lag?

Jet lag is caused by the rapid crossing of time zones outpacing your body's ability to adjust its internal clock. Your circadian rhythm shifts only gradually, about an hour or so per day, but a long flight can move you many hours in just one journey, so your body is left lagging behind local time, hence the name. The disruption is worsened by factors of flying itself, such as dehydration, cabin conditions, cramped sleep, and disrupted meal and sleep timing. Notably, jet lag is often worse when traveling east than west, because advancing your clock, going to bed and waking earlier, is harder for the body than delaying it. The more time zones you cross, the more pronounced the jet lag tends to be.

What are the symptoms of jet lag?

Jet lag brings a range of temporary symptoms centered on tiredness and disrupted sleep. The most common is fatigue and daytime sleepiness paired with difficulty falling or staying asleep at night, since your body is on the wrong schedule. Other symptoms include difficulty concentrating, poor memory or foggy thinking, irritability and low mood, headaches, and general grogginess. Digestive issues such as an upset stomach, changed appetite, or constipation are common, as the gut also runs on a body clock. You might feel generally unwell or off. Symptoms usually appear within a day of arrival and are typically worse the more time zones you crossed. They tend to ease over several days as your body gradually adjusts to the new local time.

How do you prevent or reduce jet lag?

Several strategies help you adjust faster. Before you travel, gradually shift your sleep schedule toward your destination's time, and once you arrive, adopt the local schedule immediately, eating and sleeping at local times rather than home times. Getting exposure to natural daylight at the right times is one of the most powerful tools for resetting your body clock, so spend time outdoors during the local day. Stay well hydrated and limit alcohol and caffeine, especially on the flight, since they worsen sleep and dehydration. Take short naps if needed but avoid long ones that prevent nighttime sleep. Some travelers use melatonin to help shift their clock, which is worth discussing with a doctor. Being patient helps, as jet lag naturally resolves within a few days.