This week, millions of Americans may find they feel a little more tired than usual as their biological clocks adjust to the start of daylight saving time, which officially began at 2 a.m. on Sunday, March 8.

While an hour seems like a minor change, moving the clock ahead one hour can be a significant source of stress for some people, particularly for those who are already sleep deprived. According to the National Sleep Foundation, there is an increase in traffic accidents in the days after the spring switch because drivers are less alert. In addition, Swedish researchers have linked an increase in heart attacks to the start of daylight saving time.

The problem goes beyond just the loss of a precious hour of sleep on the night of the clock change. The time change also plays havoc with the body’s circadian rhythms, or biological clock.

This biological clock, located within the brain, regulates when we feel alert and when we are sleepy. It keeps our bodies synchronized with the daily light-dark cycle of the outside world. This internal clock is "set" or fixed to the time of day by two factors: the time we regularly wake up in the morning, and our exposure to sunlight during the day. It can be reset, but (as anyone who has traveled by airplane across several time zones has experienced), the biological clock cannot be reset too quickly. 

Scientists have discovered that it is easier for our biologic clocks to adjust when we turn the clocks back an hour in October than when we turn them forward in March. Since we can shift our internal clocks at most 30 minutes earlier in one day, when we try to move the time clocks one hour earlier for daylight saving time, our bodies remain partly on the prior schedule (known as "jet lag" in plane travel). 

Daylight saving time effectively snatches morning light and adds it to our evenings. The result: 7 a.m. in daylight saving time is equivalent to 6 a.m. standard time: you can’t fool your biologically clock – your body still thinks it’s 6 a.m. Also, your typically sunlit mornings will now be dark, and that lack of morning light makes it even more difficult for your internal clock to adjust. So, not only are we losing an hour of sleep, but since it can take some time for the internal clock to readjust, we’re left feeling tired for more than the one day on which the clocks change.

People who normally sleep well can usually adjust to the time shift with relatively little trouble. However, if someone has been just managing to compensate for an undiagnosed and untreated sleep disorder, daylight saving time can exacerbate and therefore unmask problems such as sleep apnea, insomnia or restless leg syndrome.

The following tips can help you get a good night’s sleep, both during this time of adjustment and year-round:

• Be cautious not to drive if drowsy, as lost sleep and incomplete schedule adjustment contribute to drowsy driving.
• A short nap can help make up for less sleep, but naps won’t help you acclimate to the new schedule.  Don’t nap within a few hours of your regular bedtime in order to avoid disrupting nighttime sleep.   
• On the nights after the time change, go to bed at your usual time. You may experience some difficulty falling asleep, because your body’s clock  has not yet adjusted.    
• Follow these healthy sleep habits:
• Create a sleep-friendly environment that is dark, cool, comfortable and quiet.
• Have a relaxing routine before bedtime, such as soaking in a hot bath, reading for fun or listening to soothing music.
• Avoid caffeine, nicotine and alcohol for several hours prior to bedtime, as they can disrupt sleep.
• Get up at your usual clock time regularly.  Although you may find this a bit difficult, it will help you adjust to the time change.
  

If after a few days you are still experiencing daytime drowsiness, fatigue or disturbed sleep, speak to your doctor. He or she may advise that you consider consulting with a sleep medicine specialist.