|
 Consistency - going to bed and waking up at about the same time
every day, weekends included - was linked with a better grade point
average (GPA) among the college students in the study, the
researchers found.
“College students who sleep starved themselves during the week and
then binge slept on weekends had poorer grades than those whose
schedules were more consistent,” senior author Dr. Charles Czeisler,
director of the Sleep Health Institute at Brigham and Women’s
Hospital in Boston, told Reuters Health by email.
Importantly, it didn’t matter how much sleep the students got
overall. Sleep timing on its own could predict worse academic
performance, even if students made up for lost night-time sleep with
naps during the day, according to the results published in
Scientific Reports.
Czeisler and colleagues studied 61 full-time undergraduates ages 18
to 24 for 30 days. Students completed sleep diaries and the
researchers used the Sleep Regularity Index (SRI), a tool they
developed, to evaluate the students’ sleep patterns. The index is
scaled so that someone who sleeps and wakes at exactly the same time
each day scores 100, and someone who sleeps and wakes at random
times scores 0.
Those who scored in the top 20 percent were classified as regular
sleepers and those who scored in the bottom 20 percent were
irregular sleepers.
Both groups averaged about seven hours of sleep daily, though
irregular sleepers reported poorer sleep quality.
Regular sleepers were asleep 55 percent of the “clock night” – the
hours between 10 p.m. and 10 a.m. - and only 1 percent of the clock
day, whereas irregular sleepers slept for 42 percent of the clock
night and 11 percent of the clock day.
As a result, irregular sleepers experienced significantly less
daytime light and relatively more light at night, which triggered a
delay in secretion of the sleep hormone melatonin in the body,
according to the researchers.
These differences led to a body clock shift in irregular sleepers
equivalent to traveling west for almost three hours, Czeisler said,
which could explain their poorer academic performance. “For students
whose sleep and wake times were inconsistent, classes and exams
scheduled for 8 a.m. were occurring at 5 a.m. body time - a time
when cognitive performance is impaired,” he said.
[to top of second column] |
Greater sleep regularity was associated with better GPAs. Every
10-point increase on the sleep regularity index was associated with
an average increase of 0.10 points in GPA. At the end of the study,
irregular sleepers averaged GPAs of about 3.24 out of a possible
4.0, and regular sleepers averaged 3.72.
The study doesn’t prove that irregular sleep causes poorer academic
performance, the researchers note, but it could be a sign of other
daily habits that interfere with how well students do in college.
Increasing exposure to daytime light and decreasing exposure to
laptops and other light-emitting devices before bedtime might
improve sleep regularity, they suggest.
Sleep specialist Dr. Rafael Pelayo of the Stanford Sleep Medicine
Center in California told Reuters Health that while it’s possible
some people handle sleep deprivation better than others, many
students may be underperforming and not realize it.
“I compare it to having a race car,” Pelayo said. “The manufacturer
may recommend high-octane gas, but you can put cheap gas in it and
if you’re stuck in traffic, you won’t notice a difference. But if
you put it on a race track, you will. The real question is, ‘Could
you do better academically if you had better quality sleep?’”
Typically, students say when they go to bed or wake up depends on
what day it is. When they’re on different schedules every other day
and on the weekend, Pelayo noted, “the brain gets thrown off. It’s
like always being jetlagged - you’re never quite at your best.”
Instead, he advises, pick the earliest time you have to wake up, and
make that your default wakeup time for the whole week. Do the same
for bedtimes. “Do that for several weeks to get into a rhythm,
because making your sleep predictable is going to make you feel
better and do better.”
SOURCE: http://go.nature.com/2rWXLmx Scientific Reports, online June
12, 2017.
[© 2017 Thomson Reuters. All rights
reserved.] Copyright 2017 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed. |
