| Q: |
What types of disorders affect timing of sleep?
| | A: |
There are a number of problems that can affect the timing of
sleep. These disorders generally involve either voluntary or involuntary
disruption of the body’s circadian rhythm. The most common are shift-work disorder, jet lag, and delayed sleep phase syndrome (see What is delayed sleep phase syndrome (DSPS)?).
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| Q: |
What is jet lag?
| | A: |
Our body clock adjusts very slowly in response to abrupt changes
in environmental time cues. No change is probably more abrupt than that
of air travel across several time zones. Jet lag is characterized by a
group of symptoms, such as inappropriate daytime fatigue, insomnia,
early waking, disturbed sleep patterns, and impaired concentration and
alertness during the day. Other symptoms include loss of appetite,
inappropriate toilet times, and excessive urination at night.
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| Q: |
Is jet lag worse traveling eastward or traveling westward?
| | A: |
Traveling eastward shortens the day to less than 24 hours and
traveling westward does the opposite. It is easier to postpone falling
asleep than trying to get to sleep earlier than usual (which happens
when we travel east). Traveling westward generally leads to quicker
adaptation to local times. However, the severity of symptoms also
depends on other factors, including the number of time zones crossed,
flight duration, and your circadian system’s adaptibility to changes.
About a third of people who fly do not experience any significant
effects of jet lag.
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| Q: |
Is melatonin useful in combating jet lag?
| | A: |
There is some evidence that melatonin, if taken appropriately,
may assist with decreasing the symptoms of jet lag, largely by helping
the body adjust to a different sleep-wake schedule. The usual dose that
has been tested in studies is 5mg. Melatonin can reduce alertness and
induce sleepiness so you MUST NOT drive or operate heavy or dangerous
machinery once you have taken it. Short-term use of melatonin appears to
be safe although very little of the available data supports this claim.
The most common side effects are sleepiness, headache, and nausea. The
long-term effects on health are currently unknown, although there is
some evidence that there are detrimental side effects. Always use a licensed, quality-controlled melatonin preparation.
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| Q: |
If I travel EAST over several time zones, when should I take melatonin?
| | A: |
On the day of departure, take a dose of melatonin between 6 and
7pm local time (place of departure). On arrival at your destination,
take melatonin at the local bedtime (10–11pm) for 4 days. If your
stopover is shorter than 4 days, on the evening preceding your departure
back home, do not take a capsule at bedtime but at 6–7pm local time. On
arrival, take melatonin daily for 4 days at your usual bedtime if you
need to.
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| Q: |
If I travel WEST over several time zones, when should I take melatonin?
| | A: |
Do not take any melatonin before the flight. When you reach your
destination, take a dose of melatonin at the local bedtime (10–11pm) or
later, for 4 days. If you wake up very early in the morning (say around
4am) you can take another dose, but be aware that this can make you feel
very sleepy the next day.
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| Q: |
What is meant by shift-work disorder?
| | A: |
Sleep problems and other health problems arising from working
schedules outside normal daylight hours can result in shift-work
disorder. This disorder results from the interaction of social and
domestic, circadian rhythm, and sleep factors.
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| Q: |
Who is prone to shift-work disorder?
| | A: |
Although some people cope well with irregular working shifts,
those who are most likely to develop problems include people over the
age of 50, those with a history of sleep disorders (like sleep apnea or
narcolepsy), those with diabetes, epilepsy, heart disease, digestive
problems, psychiatric problems, or a history of alcohol or drug abuse.
Other factors that can impair tolerance to shift-work include a heavy
domestic workload, more than one job, and being a morning person (an
“early bird”).
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| Q: |
Can the type of shift you work lead to shift-work disorder?
| | A: |
Drawing up an appropriate shift-work roster is crucial for
optimizing performance and minimizing problems in coping with shifts.
Shifts that are harmful to well-being include: 12-hour shifts involving
monitoring tasks, heavy physical labor or exposure to harmful
substances, more than four 12-hour night shifts in a row, very early
morning shifts, split shifts with inadequate breaks, weekly rotations,
and more than 5 late-night shifts in a row.
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| Q: |
What is the impact on health of long-term shift-work?
| | A: |
People who work shifts have an increased risk of heart disease,
breast cancer, and high blood pressure, and many also have digestive
tract problems. Disrupted time with the family can have significant
impacts on people’s lives. Permanent shift-workers often have an
increased risk of mood disorders, especially depression, and abuse of
alcohol and drugs. Sleep is never entirely normal.
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| Q: |
What can I do to minimize the negative impact of shift-work on my life?
| | A: |
As well as the tips in the Strategies for dealing with shift-work,
sedatives or stimulants can be useful to regulate the sleep-wake
pattern but must be prescribed by a doctor. Weigh up the pros and cons
of shift-work and how you adapt to it. “Night owls” tend to do better
than “early birds.” After middle age, shift-work becomes more difficult
due to changes in our sleep patterns with ageing. If you have a medical
condition, reconsider whether shift-work is right for you. Changing jobs
or negotiating for alternate shifts may be an answer.
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| Q: |
What is delayed sleep phase syndrome (DSPS)?
| | A: |
This is a circadian rhythm disorder with an exaggerated “night
owl” pattern of sleep and wakefulness. Generally, speaking, a person
with delayed sleep phase syndrome (DSPS) has sleep onset and waking
times that are delayed by 3–6 hours compared to conventional sleep-wake
times. A person with DSPS feels sleepy and is ready to go to bed at
about 2–6am and gets up by 10am–1pm. Sleep itself is normal. This
sleep-wake pattern must be present for at least 3 consecutive months for
diagnosis of the condition.
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| Q: |
How common is DSPS?
| | A: |
DSPS can occur from childhood into old age. It is more common in
adolescents and young adults. Estimates suggest that about 7 in 100
adolescents and young adults have DSPS.
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| Q: |
What are the symptoms of DSPS?
| | A: |
People with DSPS cannot get to sleep before early morning and
have difficulty getting up in the morning at appropriate times. They may
complain of daytime fatigue and this may lead to impairment of school
and job performance. They are most tired in the morning and increasingly
feel more alert during the day.
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| Q: |
What causes DSPS?
| | A: |
A combination of factors results in DSPS. There are genetic
factors associated with the genes regulating the circadian rhythm–some
cases of DSPS definitely run in families. There may be subtle problems
in the regulation of the circadian rhythm
and also with the ability to recover normal sleep patterns. Behavior
and lifestyle factors that involve continued disruption of the circadian
rhythms plays a strong role in reinforcing DSPS.
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| Q: |
How is DSPS diagnosed?
| | A: |
A sleep specialist can diagnose DSPS by using techniques such as actigraphy and polysomnography if necessary. In addition, sleep diaries and the general history of the complaint can both contribute to the diagnosis.
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| Q: |
How is DSPS treated?
| | A: |
A number of different methods may be used to treat the timing
problem involved in DSPS and resetting the sleep-wake pattern. These
include light therapy in the morning or skipping one night of sleep and
“resetting” bedtime at the desired hour the next night. This should be
done under the supervision of a sleep specialist. The person may take
melatonin before bedtime.
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| Q: |
What is advanced sleep phase syndrome (ASPS)?
| | A: |
This disorder of the circadian rhythm is the opposite of DSPS.
Sleep is normal but a person has a sleep-wake schedule about 3 hours
earlier than average. A person with ASPS is very sleepy in the late
afternoon and early evening, and goes to bed early in the evening. They
get up early–anywhere between 2am to 5am. The causes, diagnosis, and
treatment of ASPS are similar to those of DSPS but targeted at different
times of the day and phases of the circadian rhythm. About 1 percent of
middle-aged adults have ASPS but it is generally not considered a
socially incapacitating problem. People with ASPS often gravitate toward
jobs that suit their extreme early morning habits.
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| Q: |
What other circadian rhythm disorders are there?
| | A: |
Other disorders include non-24 hour rhythms, in which the
sleep-wake cycle does not run on the rhythm of a normal 24-hour day.
Certain forms of blindness can cause problems with circadian rhythms and
timing of sleep.
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