Jetting off for a vacation before the summer ends? The anticipation of taking a time-out and getting away from the rigors of daily life can be exhilarating… until you get to your destination feeling tired, tense, and touchy thanks to jet lag.

Crossing multiple time zones can play funny games with your circadian rhythm. If you are traveling from New York at 8 a.m. to California and it’s a five-hour flight that crosses three time zones, that means you land at 10 a.m. L.A. time. But it’s really 1 p.m. your time back in New York and starting an afternoon romp through Disneyland with the kids works out great. Consider the reverse, however: Say you leave L.A. at 5:30 a.m. to get to New York for a 1 p.m. meeting in downtown Manhattan (without the kids). If getting up that early is not normal for you, you would do well to take a nap on the flight so you’re refreshed by the time you land in New York. Or leave later in the morning from L.A. and schedule the meeting for the following day so you have time to adjust.

Adjustment. That’s the key word when it comes to jet lag, and for good reason. When your internal clock doesn’t match the external clock, it can be– and feel — like World War III in your body. The problems that arise with jet lag are a clear example of how external influences can disrupt our internal body clock.

I’ve blogged about biological clocks before. It’s a fascinating area of research that has so many applications to everyday life. Consider how much your internal clock determines the quality of your life. And if you don’t know what I mean by that, then here’s a quick summary of the role your internal clock plays:

• Your sleep/wake cycles.
• How refreshed you feel in the morning.
• How easy it is for you to fall asleep at night.
• Whether you can recover quickly from jet lag.
• The fate of a shift worker who has to be productive at odd hours.
• Whether you’re a lark or an owl.
• Your mood and energy level.
• The strength of your immune system.
• Your ability to ward off diseases, including cancer and Alzheimer’s.

It may seem hard to believe that your body’s clock can influence diseases like cancer, but it’s true. Think of your clock as your body’s central pacemaker — a means by which the body can remain balanced and, in medical speak, in a state of homeostasis. An entire network of molecular clocks found in the different organs coordinate the body’s various physiological processes ranging from the heart beat, temperature, sleep requirement and hormone balance to behavior. All of these clocks are controlled by the master pacemaker of the hypothalamic suprachiasmatic nuclei (SCN), which synchronizes all of the body’s “peripheral” clocks with the outside world. At the molecular level, all of the clocks are based on a handful of “clock” genes and proteins that regulate each other interactively and thus generate a molecular time signal in the form of a circadian rhythm, a term that originates from the Latin for approximately (circa) and day (dies).

Research continues to emerge helping us understand our clock — or even clocks. Just last month, researchers at the Max Planck Institute for Biophysical Chemistry published a study in the Journal of Clinical Investigation demonstrating (at least for mice), that the clocks associated with individual organs in the body adapt to the new time at different speeds. So while you feel out of whack once you reach a new time zone, it’s pretty much because your body’s physiological processes are no longer coordinated. And the adrenal gland plays a key role in this process. When the researchers switched off the adrenal clock or manipulated the synthesis of the hormone corticosterone by the adrenal gland, the rodents adapted more quickly to the altered circadian rhythm. These insights could pave the way for a new approach to the hormonal treatment of the effects of jet lag and shift work.

These findings surprised even the scientists. It marks the first time that anyone has systematically studied how individual “clock” genes and the internal clocks of the different organs synchronize with the new external time in the case of jet lag.

So what can you do to prevent the jet lag from making your trip a drag? How about setting your body clock to a new time zone before the journey? By using light therapy or an alarm clock that simulates dawn and dusk with techniques to induce sleep, you can reset your circadian body clock before a journey, thus preventing jet lag from the very start. If you are planning a trip across more than two time zones and want to get accustomed to your destination’s time zone quickly, this might be an approach to take.

Let’s say you have an important business trip for which you have to fly east. Before flying, you’d go to bed and wake up earlier each day while using a light box in the morning and winding down earlier in the evening. If you’re traveling west, you would expose yourself to bright light later in the day, go to bed later and wake up a little later in the morning.

If you don’t have the time or inclination to get a light box, then consider direct sunlight as the next-best alternative. Light boxes, while producing artificial light that mimics the sun’s intensity, don’t emit ultraviolet radiation. They are designed to produce those perfect wavelengths of light (peaking in the optimal “blue” wavelength range, or 460 nanometers) and the light gets directed angularly at your eyes for the greatest effect.

If you can shift your body clock naturally prior to departing, this can be a particularly useful technique if your trip doesn’t allow for much time to adjust before kicking into high gear and demanding your top performance.

Try and switch over to your new time zone right away by going to bed and getting up at the same time you would normally, but on this new time zone. So if you usually go to bed at 10 p.m. in L.A., do the same the first night you land in New York even though your body might think it’s only 7 p.m. Then, the next morning try and go for a walk outside, exposing yourself to light and movement that can help re-set your internal clock.

And take my Traveler’s Survivor Kit with you:

• Ear plugs
• Eye mask
• Favorite soothing music and head phones or a device like an iPod
• C-shaped pillow that fits around your neck

These strategies can also be used for shift workers. But that’s another story for another day

Bon Voyage and Sweet Dreams