Disturbances of sleep timing
Date Posted: October 1, 2007
In-Depth Report
Disturbances of sleep timing
When their internal clocks are disturbed, people may long for sleep when they need to be awake or may stay up until the wee hours of the morning without feeling tired.
Delayed sleep phase syndrome
Almost everyone is programmed for a day that lasts slightly longer than 24 hours, but "night owls" are less sensitive to the environmental cues that help most people maintain the usual 24-hour cycle. Left to their own devices, they would generally go to sleep and wake up much later each day. Only by relying on external cues, such as alarm clocks, do they manage to stay in sync with a more conventional schedule. Night owls have trouble getting anything done in the morning.
They may be able to gradually synchronize their schedule with others by going to bed and getting up at the same time every day. However, it's easy for their sleep patterns to go awry when they go on vacation or retire. Night owls often find that a minor shift in sleep/wake cycles such as the onset of daylight savings time, a coast-to-coast trip, or a weekend of late-night parties can throw them off kilter unless they force themselves to get up at the same time every day.
Resetting your internal clock
Exposure to bright light as directed by a sleep specialist — a technique known as light therapy — may be useful in treating delayed sleep phase syndrome. Upon awakening, patients typically sit for 30 minutes facing a specially manufactured box that emits bright light with a minimal amount of ultraviolet light.
Another option is to move your bedtime progressively later until you've shifted around the clock and are back in sync. To do this, go to bed two hours later each night. Once you have synchronized your schedule to match that of the other people around you, wake yourself up at the same time each day.
A delayed sleep phase also can be reset in a single weekend. This requires staying up all night on Friday and all day Saturday, then going to bed around 10 p.m. On Sunday, get up at 7 a.m. From then on, adhere closely to the same bedtime and waking time seven days a week.
Melatonin may also have a role in treating delayed sleep phase syndrome; taking 3 to 5 milligrams three hours before your current bedtime may help advance your sleep schedule.
Advanced sleep phase syndrome
People whose body rhythm cycles are shifted much earlier go to bed earlier, wake up in the early morning, and eventually can't stay awake past early evening. This condition, called advanced sleep phase syndrome, is more common among older people. Treatments being studied include bright light therapy in the evening, which helps reset the body's clock, and carefully timed doses of melatonin.
Jet lag
Many people find that crossing several time zones makes their internal clocks go haywire. In addition to having headaches, stomach upset, and difficulty concentrating, they may suffer from fitful sleep.
Younger people usually adapt more quickly to time changes than older people. It takes about a day to adjust for every time zone crossed. Many people have more difficulty traveling eastward, but older people may have more symptoms traveling westward.
The standard way to handle jet lag is to try to sleep only at night upon arrival and to get up early in the morning, although it may be difficult the first few days. This way your body can start adjusting to the new time zone as soon as possible (see "Ways to avoid jet lag"). Short-term use of timed doses of melatonin or Rozerem to shift circadian rhythms or over-the-counter or prescription sleep aids to help you sleep at night also can be helpful.
Ways to avoid jet lagDon't time-shift. On a brief trip just one or two time zones away, it may be possible to wake up, eat, and sleep on home time. Schedule appointments for times when you would be alert at home. Gradually switch before the trip. An hour at a time, move mealtimes and bedtime closer to the schedule of your destination. Even a partial switch may make the trip easier. Switch as rapidly as possible upon arrival. On a long trip, don't turn in until it's bedtime in the new time zone. For the first day or two, spend as much time outdoors as possible to let daylight reset your internal clock. Use the sun. If you need to wake up earlier in the new setting (flying west to east), get out in the early morning sun. If you need to wake up later (flying east to west), expose yourself to late afternoon sunlight. Drink plenty of fluids, but not caffeine or alcohol. Caffeine and alcohol promote dehydration, which worsens the physical symptoms of jet lag. They can also disturb sleep. |
Sunday insomnia
People often have trouble falling asleep on Sunday nights. While anxiety about work or school on Monday is a potential cause, often the most important factor is weekend changes in sleep habits. When you stay up later Friday night and sleep in Saturday morning, you are primed to stay up even later Saturday night and sleep in the next day. By Sunday evening, your body's clock is programmed to stay up late. People who have developed a pattern of Sunday insomnia may feel their anxiety mount as they anticipate a difficult night ahead.
The best way to avoid the Sunday blues is to maintain the same wake-up and bedtime on the weekends as during weekdays. If this isn't possible and you end up staying up later than usual on Friday and Saturday, the next best thing is to force yourself to get up at your weekday wake-up time and take an early afternoon nap on Saturday and Sunday. This way, you maintain the same wake-up time while still compensating for your sleep deprivation.
Shift work
More than 20% of American workers — including health care workers, police officers, security guards, and transit workers — are on the evening or night shift. About 60% to 70% of shift workers experience sleep disturbances. These people fall asleep on the job two to five times more often than day-shift workers do. Sleepiness can be catastrophic for people in these vital roles. Sleep-deprived physicians, for example, make a greater number of errors than their better-rested colleagues, and it's common for fatigue to play a role in overnight rail, plane, truck, and maritime accidents.
Shift workers' sleep disorder can be eased somewhat by incorporating scheduled breaks, by rotating shifts from day to evening to night rather than the other way around, or by maintaining the same schedule seven days a week. Shift workers can also benefit from practicing good sleep hygiene (see "Tips for a better night's sleep"). Dark curtains or eyeshades can keep daylight out, and running a fan can help block external noise. Shift workers need to enlist the help of family members to get enough sleep while maintaining a schedule at odds with the rest of the world. The most successful shift workers are those who block out time for sleep in advance and then are vigilant about protecting their sleep time from outside intrusions. Light therapy is sometimes recommended to help people get used to a new schedule, as is the short-term use of sleep medications.
Seasonal affective disorder
In some parts of North America, winter means less exposure to sunlight. As the days get shorter, some people find themselves depressed, sleepy, and drawn to high-carbohydrate foods.
Researchers speculate that people who suffer from this condition, called seasonal affective disorder (SAD), produce too much melatonin (or are extra-sensitive to normal amounts of this drowsiness-inducing hormone) and don't make enough serotonin, which may induce the craving for carbohydrates. Exposure to bright light in the morning for 30 minutes may alleviate the symptoms of SAD and help people wake up in the mornings. Antidepressants can also be helpful.
Review Date: 2007-10-01
Harvard Medical School does not endorse products or services.
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