IS IT BEDTIME... OR LUNCHTIME? JET LAG CAN WAYLAY THE UNWARY ON TRIP TO AUSTRALIA.

Byline: Eric Noland Travel Editor

Consider them among the peculiarities of international air travel.

Sydney, Australia, not only is 18 hours ahead of Los Angeles (19 hours during daylight savings) but also lies on the other side of the international date line, which bisects the Pacific Ocean. Thus, on an outbound flight, you virtually kiss an entire date off the calendar, never to retrieve it. And on the return trip, you essentially arrive before you left.

This can create some genuine challenges in combating jet lag, while also placing a high premium on in-flight comfort.

Air New Zealand, Qantas and United are the three airlines that work the Los Angeles-Sydney route. They commonly leave L.A. late in the evening, thus timing their arrival with the early morning - though two days hence.

A passenger departing L.A. at about 10 on a Sunday evening, for example, will endure close to 15 hours in the air, see Monday flash by somewhere over the Pacific, and arrive at about 7 a.m. on Tuesday. (If you're at the age where you dread marking birthdays, it might be a good idea to schedule yours to coincide with that lost day.)

On the return, a flight leaving Sydney at 11:30 a.m. will spend 13-plus hours in the air and arrive in L.A. just after 6 a.m. on the very same day.

To overcome the whiplash strains on the body that result from these dramatic time differences, doctors generally advise passengers to begin making the switch to the destination time schedule as early as possible - before you leave, in fact.

``It's important not only for enjoying a vacation trip, but important for performance in business - to be sharp for a negotiation, for example,'' said Dr. Robert Huizenga, a Beverly Hills internist. ``I think it's a good idea when flying to Australia to stay up as late as you humanly can and wake up as late as you humanly can on the two or three days before you leave.''

Before our trip in October, we attempted to do exactly that. Huizenga also urged us to fight off sleep for as long as possible on the outbound flight. Other passengers may be conking out soon after the 10:15 takeoff, but it's a good idea to watch movies (they were shown continuously on our Air New Zealand flight), read, eat, walk around and try to stay awake for the first five or six hours of the flight, even if that would be equivalent to staying up until 3 a.m. or later Los Angeles time.

Then it's off to sleep - if you're lucky - for the final seven or eight hours of the flight. That way, you'll be waking up at about 6 or 7 on the morning of your arrival in Australia.

To enhance your chances of zonking over a period of time when you're normally wide awake and at your desk in the morning, there are some over-the-counter and prescription medications available, many of which have minimal groggy side effects. But everyone reacts differently to them, so it is essential to consult a physician before taking anything.

Upon arriving in Australia in the early morning, the worst thing you can do is go straight to your lodgings and tumble into bed. Instead, eat breakfast, plan a full day - preferably one that will involve walking around in the sunshine - and fight through any fatigue. Coffee can be a good aid in this regard. (Don't undertake anything as strenuous as the Sydney Harbour Bridge climb, however.)

In the afternoon - at about 3 p.m. or so - you can lie down for a nap, but by all means set an alarm for 5 p.m., then force yourself to get up. In the evening, go out, have dinner at the normal time, and again try to stay up until 10 or later. This method won't ensure that you adjust quickly, but it will help.

For the return flight, Huizenga advised us to reverse the sleep pattern: Try to go to bed early on the few nights leading up to the departure, and set alarms to rise early, so as to begin the readjustment to Los Angeles time.

Then, on the flight home, although it might be only 6:30 p.m. body time, attempt to nod off for the final seven or eight hours preceding a dawn arrival back home. For some reason - perhaps it was the screaming babies in coach or the difficulty of sleeping when the sun was blazing outside - we found it much more difficult to nod off on the return trip.

Huizenga believes the airlines could better guide travelers through the wrenching changes by controlling the in-flight environment. ``They should adjust the plane to the time of where you're going - close the shades to simulate nighttime, use bright lights to simulate daytime,'' he said.

At least the comfort level of the Air New Zealand flight aided in our adjustments. On many carriers, the service in the forward cabins tends to be friendly and responsive, while flight attendants in the back of the plane often exhibit a combat-weary gaze, with matching demeanor. But we found the flight attendants in coach to be attentive and unfailingly cheerful.

A lamb stew dinner was perhaps the best food we'd ever had on an airplane, and the crew was liberal with its pouring of some reputable Australian wines. (Abstinence from alcohol is said to be another method for minimizing jet lag; it's a tenet we stubbornly disregard when on vacation.)

More importantly, flight attendants also dispensed bottled drinking water freely. That is essential in mitigating the dehydration that is common when spending 14 hours at 30,000 feet.

The configuration of the 747-400 jet - three seats along each side in coach, four seats in the center section - isn't particularly well-suited to couples, but at the very back of the plane there are three rows of just two seats along each side. It may be disconcerting to have a boarding pass that indicates row 57, but aside from the restroom line that occasionally extended into our vicinity, we found it preferable to being clumped together with another passenger for such an extended period.

The coach seats on these long-distance carriers also have sleep- friendly features normally found only in first and business classes domestically - adjustable, wing-like supports on the headrests, and adjustable footrests.

--Air New Zealand: [phone], [phone]; www.airnewzealand.com.