You’ve just flown halfway across the globe, and the clock tells you it’s morning but your body tells you it’s bedtime. You’re tired and dazed. You can’t think straight and it takes days to feel normal again. Jet lag. Is it just an annoyance, or a serious health threat? And among the many touted remedies, could a new smartphone app be the answer?
My guess is that if you’ve ever flown across multiple time zones, you’re familiar with the effects of jet lag. More than just tiredness, jet lag can make you feel like you’ve been hit by a truck. Disoriented, confused and without any appetite or ability to engage in conversation.
Jet lag happens when your master body clock (located in the hypothalamus of the brain) is disrupted and ends up out of sync with your new location. It only happens when you cross multiple time zones, so travelling north-south isn’t a problem. And most people find jet lag is worse when they travel eastwards rather than westwards because of the difference between losing and gaining hours in the day.
How jet lag works
Your internal body clock drives your circadian rhythms, including everything from your body temperature and periods of alertness to your blood pressure and appetite.
Your body clock is largely under the control of light – there are special cells in your retina that tell your brain what time it is. And being exposed to bright light at different times can make your body clock speed up or slow down.
The reason light has such a strong effect is because of the hormone melatonin (produced by the pineal gland near the centre of the brain). Levels of melatonin vary according to a 24-hour cycle. Your melatonin levels start to go up about two hours before you go to sleep, helping you to feel drowsy. So being exposed to daylight when your body clock thinks it’s night leaves your body completely out of whack.
Just annoying, or more serious?
Repeated disturbances to body clock rhythms (think frequent flyers and shift workers) has been linked to diabetes, heart disease and depression. But even infrequent flyers may face problems.
Scientists have shown that jet lag can have serious long-term effects on both our brains and waist-lines.
Research on hamsters that were subjected to six-hour time shifts showed that even a month after returning to their normal day-night schedule, the animals still had serious memory and learning problems. Hamsters were used for the study because they have very clear natural body rhythms.
In another study, airline cabin workers who experienced frequent disruptions to their body clocks with little rest between flights had smaller temporal lobe structures in their brains. That’s right, part of their brains had shrunk – one of the parts of the brain involved in storing and retrieving memories.
Your gut microbes also have rhythms that are in sync with your body clock. Research out last month showed that when your body clock gets out of sync, the composition of your gut bacteria is disrupted, leading to gut problems and potentially even obesity in frequent flyers.
What’s the fix?
There are many different remedies for jet lag, some more effective than others. We’ve all heard that we should drink lots of water and no alcohol on the plane and stay awake until nighttime at our destination.
Other people get a doctor’s prescription for melatonin tablets, which can be used to help shift the body clock. But many people want to be able to minimise jetlag without taking drugs.
There is no silver bullet – so far – to treat jet lag. Horacio de la Iglesia, Professor of Biology at the University of Washington
The best way to avoid or minimise jet lag drug-free is to change your internal schedule to suit the time zone you have just travelled to. How do you do that? Simply plan extremely carefully when you spend time in daylight and when you should hole up in a dark room. You can even begin to pre-adjust to your new time zone before you leave home. Sound complicated?
These days there seems to be an app for everything and jet lag is no different. Mathematicians from the University of Michigan have developed a free iPhone app called Entrain. It uses mathematical equations to model your body clock and create a custom light/dark schedule so you can adjust your internal clock to the new time zone as quickly as possible.
By answering some questions about when you usually fall asleep and wake up and in which time zone you normally live, Entrain calculates what time your body thinks it is right now. You then input the new time zone and information about the brightness of the lighting you will be exposed to. The brighter the light you can expose yourself to at the right times, the faster you will adjust!
In addition to the schedule you need to follow, the app tells you the time it will take “to Entrain” to your new time zone. By following the maths, you can fully sync to a 12-hour shift in time zone in only four days (and you should be sleeping well after only two days).
Whoever said maths isn’t relevant to daily life?