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Your inner clock



This past week endocrinologists convened in Manila for the 20th ASEAN Federation of Endocrine Societies (AFES) Congress with attendees from all over the world. Most stay for only a few days and this does not give them much time to adjust to a new time zone.

Whether you travel for work or for leisure, international travel can cause some discomfort, such as temporary disturbances in sleep or what we commonly call jet lag, since it is mostly related to air travel.

The body has an internal clock, or a circadian rhythm, that tells your body when to stay awake and when to sleep. Jet lag happens when you travel quickly to another time zone and your body’s clock is still synced to your original time zone.

For jet lag to occur there must be an east-west or west-east movement and more than two time zones crossed.

Jet lag is temporary, but it can disrupt your sleep and cause daytime fatigue. This can hamper your vacation or business trip, and if you need to be alert during the day, it can be difficult to adjust right away.

Symptoms of jet lag can vary, and usually occur within a day or two of travel. The most common is disturbed sleep — insomnia, early waking or excessive sleepiness. Other symptoms can be difficulty concentrating, irritability and problems with digestion.

Jet lag is also worse if you travel in an easterly direction when you “lose” hours, such as travel from North America to Asia. It usually takes about a day to recover for each time zone crossed.

For example: If you take a 14-hour flight from San Francisco to Manila, when you leave at 6:00 a.m. on a Monday and land at 11 a.m. Manila time on a Tuesday, your internal clock is still on San Francisco time and thinks it’s 8 p.m. on Monday, and your body is beginning the wind-down to bedtime while it is only mid-day in Manila. It can be about 1 week before your body is on Manila time.

On the other hand, traveling westward (e.g. Manila to San Francisco) adds hours to your day and your body has more time to recover and adjust to the new time zone.

Fortunately, there are steps you can take to help prevent or minimize jet lag.

Get some rest. Starting out already sleep-deprived before your trip can make jet lag worse.

Make gradual adjustments ahead of time. If traveling from Manila or towards the western hemisphere, try to go to bed one hour later for successive nights for a few days before your departure. So if you usually sleep at 9 p.m., two days before your trip sleep at 10 p.m. and then at 11 p.m. the next day, which is the day before your planned departure. Sleep for the usual number of hours and wake up later.

And if traveling home to Manila or eastward, go to bed and wake earlier for a few days before departure.

Adjust your diet. If possible, eat meals closer to the time you’ll be eating them at your destination. Also try eating a little more protein to stay alert and carbohydrates when you want to sleep.

Stay hydrated. The air inside an airplane cabin is drier and if you don’t drink enough you can become dehydrated which worsens the symptoms of jet lag.

Avoid alcohol on the plane. Drinking alcohol increases the need to urinate, which can disrupt sleep. While alcohol often induces sleep, the quality of sleep will be lower. And the hangover effect of alcohol can worsen the effects of jet lag and travel fatigue.

Sleep on the plane if it’s nighttime at your destination. Use earplugs and eye masks or sunglasses to block out noise and light. Take a few short naps (20 minutes) at other times.

Stay on your new schedule. Set your watch to the time of your destination as soon as you board the plane. Once you arrive, try not to sleep until the local nighttime, no matter how tired you are.

Regulate exposure to bright light. Exposure to light is one of the greatest influences on your body’s circadian rhythm. In general, exposure to light in the evening helps you adjust to a later than usual time zone, while exposure to morning light can help you adapt faster to an earlier time zone.

The one exception is if you have traveled more than eight time zones from your original time zone, because your body might mistake early morning light for evening dusk.

So, if you’ve traveled more than eight time zones to the east, wear sunglasses and avoid bright light in the morning, and then allow as much sunlight as possible in the late afternoon for the first few days in your new location.

If you have traveled west by more than eight time zones, avoid sunlight a few hours before dark for the first few days to adjust to the local time.

Use caffeine properly. Beverages with caffeine may help offset daytime sleepiness. But avoid caffeinated beverages after midday since this may make it even more difficult to fall asleep or sleep well.

Jet lag often does not need treatment, but melatonin can sometimes be used to help you sleep once you get to your destination, taken 1-3 hours before your desired time of sleeping. Talk to your doctor about the right dose for you and also if you have to adjust the timing of any other medications you may be taking.