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Adolescents
Last edited |
10/21/2008
Despite the
inherent importance of sleep there is scant information available on the
epidemiology of sleep behaviors (Levy et al., 1986; Morrison et al., 1985) and
sleep disturbances among youths (Anders and Eiben, 1997; Dahl, 1996; Richman,
1987)
By way of illustration, Ohayon and Guilleminault (1998) reviewed all
epidemiological surveys of sleep disorders published over a 20 year
period. They were looking for studies on insomnia, excessive sleepiness,
sleep‑disordered breathing and parasomnia: not
even one had adolescent sleep problems as a focus.
Adolescence is accompanied by various biological changes including a
modification of sleep-wake regulation and sleep patterns (e.g. decrease in the
amount of Delta sleep, reduced REM latency).
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According to Carskadon (1990),
adolescents require more sleep than prepubertal youths but frequently get less
sleep than they need.
Transition to an earlier school‑start time, along with
sleep phase delay, significantly affects teenagers' sleep quality, sleep/wake
schedule, and daytime behavior.
The combination of the phase advance, late night
activities or jobs, and early morning school demands can significantly constrict
hours available to sleep (Wolfson, 1985).
But do these changes attributable to
adolescence translate into higher prevalences of sleep disorders? It is unclear.
Our knowledge about normal as well as abnormal sleep patterns in school‑aged
children, particularly adolescents, is represented by a relatively small body of
literature (Dahl, 1996; Levy et al., 1986; Morrison et al., 1985; Richman, 1987; Wolfson and Carskadon,
1998).
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It is clear from the few community and school‑based
studies examining the prevalence of sleep disturbances in youths that symptoms
of disturbed sleep are common. Some
examples:
• between 5 and 12% of a sample of youths in Florida complained of
insomnia (Karacan et al., 1973);
• another study found 18% of junior high
students complained of falling asleep in school (Anders et al., 1978).
• two other studies report that at least 12% of adolescents
suffered from chronic poor sleep (Levy et al., 1986; Price et al., 1978).
• a survey of ninth and tenth grade
students classified 11% of students as chronic poor sleepers and 23% as
occasional poor sleepers (Kirmil‑Gray et al., 1984).
• using data from a national survey, Cornelius (1991)
reported that adolescents were over eight times more likely than children to
sleep six hours or less per night, and only half as likely to sleep nine or
more hours per night.
• based on data from a national
survey in France, Ohayon (1997a) estimates the prevalence of DSM‑IV insomnia to
be 12.5% for those 15‑24 years of age. In a similar study in the United Kingdom,
the prevalence was 4.4% for severe daytime sleepiness and 14.3% for moderate
daytime sleepiness for those aged 15 to 24 (Ohayon et al., 1997b).
Other than these two
latter studies, neither of which analyzed data separately for adolescents, most
of the research has been school-based rather than community-based.
It is difficult to
interpret the prevalence rates due to variability in operational definitions,
sample populations, and assessment techniques.
To
our knowledge, only one community‑based, epidemiological study has been carried
out using definitions of sleep problems based on either DSM diagnostic criteria
(APA, 1994) or the International Classification of Sleep Disorders (ASDA, 1991).
Morrison and his co-authors (1992) used DSM‑III and the DISC in their study of
15‑year‑old New Zealand adolescents.
To meet criteria,
youths had to report a sleep problem at least four times per week for four
weeks.
Using this definition,
33% of the sample overall had at least one sleep problem in the previous four
weeks.
The prevalence of
those who had difficulty falling asleep, staying asleep, or waking too early
(i.e. insomnia) was 15.2%.
The
DSM-IV includes a chapter devoted to the sleep disorders.
It covers dyssomnias
(characterized by abnormalities in the amount, quality or timing of sleep) and
parasomnias (sleep disorders characterized by abnormal behavioral or
physiological events occurring during sleep or during sleep-wake transitions).
Dyssomnias are disorders of initiating or maintaining sleep or of excessive
daytime sleepiness.
It includes insomnia, hypersomnia, narcolepsy,
breathing-related sleep disorder, circadian rhythm disorder and a residual
diagnosis. Parasomnias include nightmares, sleep terrors, sleepwalking and a
residual diagnosis.
Research
Our purpose here was to provide
additional data on the prevalence and patterns of problematic sleep among
adolescents using DSM criteria.
Results
Differences between adolescents and young adults
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4% of the adolescents met DSM‑IV criteria for insomnia.
This was comparable to the young adult group.
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At least one insomnia symptom was
reported by nearly 25.7% of the adolescents; this was comparable to the rate for
young adults.
The rate of nearly 26% is comparable to that reported in U.S.
school‑based samples (Dahl, 1996; Roberts et al., in press) and in a French,
school‑based study (Choquet et al., 1988).
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Not surprisingly, the
prevalence of insomnia symptoms was quite high in those with anxiety or
affective disorders.
Nearly three‑fourths of both adolescents and young adults
with a DSM‑IV diagnosis of an anxiety disorder had at least one symptom of
insomnia.
For those with an affective disorder, 68% of adolescents and 77% of
young adults reported at least one symptom of insomnia.
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The
prevalence of circadian rhythm disorders was very low among adolescents (0.4%).
Contrary to other findings, we did not find a higher rate of circadian rhythm
disorders in adolescents than in young adults.
We observed, however, a higher
occurrence of indicators of such disorders in adolescents (for example,
differences between the real and wished sleep‑wake schedule; extra sleep on days
off; difficulties to get up in the morning).
This is insufficient
to establish a sleep phase delay or advance syndrome which requires at least
daytime repercussions on functioning.
A regular sleep‑wake schedule, such as
required by school or work schedules, protects against such a desynchronization
by daily resetting the internal pacemaker.
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In this way, sleep/wake schedule data
obtained in this study are different from that reported in previous work with
American adolescents (Carskadon, 1990; Wolfson and Carskadon, 1998). I
n these studies, the adolescents surveyed had a later bedtime and an earlier
rise time than in our European sample of adolescents and consequently, a shorter
sleep time.
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However, we found a similar migration of bedtime across age. School schedules in
USA high schools are different from those of European schools.
For example in France, school start time is around 8:30 AM and school ends
between 4:00 and 5:00 PM.
Adolescents never have school on Wednesday but they go to school on Saturday.
In Germany, adolescents go to school from 8 AM to 1 PM.
On rare occasions, they have school in the afternoon.
Later school start time appears to be more congruent with adolescent rhythm of
life.
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The
results of this study clearly show that sleep habits change considerably between
late adolescence and young adulthood. Indeed, usual bedtime and wake up times
are earlier in late adolescence than in young adulthood.
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Sleep
is also longer and less disrupted in adolescents.
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Not so
surprising, more adolescents than young adults would like to wake up later in
the morning. The extra amount of sleep got on weekends and days off also is more
important in adolescents than in young adults.
How do our data compare to those from other studies?
As noted earlier, only one
community‑based, epidemiological study has been carried out using definitions of
sleep problems based on either DSM or ICSD diagnostic criteria.
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Morrison and his co‑authors (1992) report 33% of the sample overall had at least
one sleep problem in the previous four weeks.
The prevalence of those who had difficulty falling asleep, staying asleep, or
waking too early was 15.2%.
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A
survey by Yang et al. (1987) of 12 to 18 year‑olds in China found 14.9% of these
adolescents reported difficulty falling asleep at least four nights in the past
month.
Beyond
these three studies, the results are quite disparate, reflecting diverse
samples, diverse study designs, and diverse measures of disturbed sleep.
Most
of the studies have used measures of sleep problems idiosyncratic to their
particular study.
Not
surprisingly, since no two studies have used the same definitions or measures,
the rates of sleep problems reported have varied widely.
Studies have defined the need for more sleep, wish for more sleep, daytime
sleepiness, nightmares, non‑restorative sleep, grinding teeth, difficulty
maintaining sleep, difficulty initiating sleep, early morning waking, sleep
talking, sleep walking, and more as being reflective of " having a sleep
problem" .
Perhaps the most frequently used measures have been those directed at problems
with insomnia, using some combination of difficulties falling or staying asleep
or waking too early.
Prevalences from these studies range from 6% to 35% (Anders
et al., 1978; Andrade et al., 1993; Coren, 1994; Kahn et al., 1989; Stoleru et
al., 1997). However, most fall in the 11‑15% range (Levy et al., 1986; Kirmil‑Gray
et al., 1984; Manni et al., 1997; Morrison et al., 1992; Strauch and Meier,
1988; Yang et al., 1987).
Our prevalence for any symptom of insomnia was 30%,
clearly in the upper range of reported prevalences.
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Sleep-EVAL
Research
