SLEEP AND THE TEENAGER, by Stacie C. Link and Sonia Ancoli-Israel
http://bisleep.medsch.ucla.edu/WFSRS/abstracts/htdocs/ab100.html

Studies have suggested that during the teenage years, the sleep / wake 
cycle becomes delayed and therefore many teenagers experience delayed 
sleep phase syndrome. Other studies have also suggested that students 
with poor sleep habits do not do as well academically in school. This 
study surveyed sleep habits in high school students to determine 
whether in fact this age group was sleep delayed and whether students 
with higher grade point averages got more sleep than students with 
lower grade point averages.

Method

150 high school students (56 boys and 94 girls; mean age = 16.2 years, 
range = 15-18 years), enrolled in either biology, physiology or physics 
classes, participated in this project. A questionnaire containing 37 
questions dealing with demographics, sleep environment, sleep patterns, 
times to bed, times wake, general sleep information and grade point 
average was distributed.  Every subject was required to fill out a 
permission slip prior to filling out the questionnaire. Analyses were 
done comparing GPA with sleep variables using Spearman Rank Order 
Correlation, Kruskal-Wallis Analyses of Variance and Chisquare.

Results

Data from school nights vs. non-school nights were compared to 
determine if the student's sleep patterns were delayed. Overall, the 
students' sleep habits were as follows: 

                                                  Mean
            School Days:
            Time to bed                           22:44
            Time up                               05:55
            Total time asleep                     7.18 hours
            Number of naps                        .52

            Non-School Days:
            Time to bed                           24:41
            Time up                               09:51
            Total time asleep                     9.17 hours
            Number of naps                        .34

            Average Night:
            Time to fall asleep                   29.4 minutes
            Number of awakenings                  1.3

            GPA                                   2.90


Correlations indicated that on school days, the later the students 
reported going to bed, the more naps they reported taking (rs=0.18; 
p<0.05) and the later they reported going to bed, the harder it was for 
them to wake up (rs=0.21; p<0.01).

Correlations comparing the association between GPA and sleep patterns 
indicated that the higher the GPA, the later the students reported 
waking up on school days (rs=0.30; p<0.001). the earlier they reported 
waking up on weekends (rs=-0.18; p<0.05), the less time they reported 
it took to fall asleep (rs=-0.22; p<0.01), the fewer times they 
reported waking up at night (rs=-0.29; p<0.001) and the less naps they 
reported taking on school days (rs = -0.25; p<0.005).

Subjects were divided into two groups with either GPA>=3.5 or GPA<3.5 
38% of the students with lower GPAs reported falling asleep or fighting 
to stay awake while riding a bus or in a car compared to only 23% of 
those with higher GPAs (chi square=7.47, p=0.006). There were 
significant differences with the group with GPA>=3.5 reporting waking 
up later on school mornings (0608 vs. 0549, p<0.004), waking up less 
often during the night (.93 vs. 1.5, p<0.0005) and taking less naps 
(.29 vs. 63, p<0.036). There was also a trend for them sleeping longer 
at night on school nights (7.4 vs. 7.0 hours, p<0.07).

Conclusion

These data indicate that students who have higher GPAs sleep more at 
night and are less sleepy during the day than students with lower GPAs. 
One interpretation of these results is that students who get more sleep 
have higher GPAs because of their ability to be more alert and pay more 
attention during class. When students are allowed to sleep as much as 
they want (i.e., non-school days), they tend to go to bed at a later 
time, wake up later in the morning and sleep longer. These sleep 
pattern suggests a delayed sleep phase syndrome with sleep deprivation 
during the week. These results are in agreement with other studies 
which have also shown that many teenagers suffer from delayed sleep 
phase syndrome.