College students who go to sleep and get up at different times during the week may be damaging their academic performance, says a US study. Regularity in sleep timings going to sleep and waking at around the same time daily including weekends included — was related 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 e-mail.
Importantly, it didn’t matter how much sleep the students got overall. The sleep timings of the students itself was a forecaster of bad academic performance. It did not matter 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 examined the sleep of 61 full-time undergraduates ages 18 to 24 for 30 days. Students concluded sleep diaries and the researchers used the Sleep Regularity Index (SRI), an instrument they developed, to analyse the students’ sleep patterns. The index is scaled so that someone who sleeps and wakes at the same time each day scores 100, and someone who sleeps and wakes at random times scores 0.
Those who ranked in the top 20 per cent were labelled as regular sleepers and those who scored in the bottom 20 per cent were irregular sleepers.
Both groups averaged about seven hours of sleep daily, though irregular sleeper also reported inferior sleep quality.
Regular sleepers slept for 55 per cent of the “clock night” — the hours between 10pm and 10am — and only 1 per cent of the clock day, whereas irregular sleepers only slept for 42 per cent of the clock night and 11 per cent of the clock day.
As a result, irregular sleepers faced considerably less daytime light and relatively more light at night, which sparked a delay in secretion of the sleep hormone melatonin in the body, according to the researchers.
These differences led to a shift in the body clock of in irregular sleepers which was equal to traveling west for almost three hours, Czeisler said, which could be a possible explanation for their poorer academic performance. “For students whose sleep and wake times were inconsistent, classes and exams scheduled for 8am were occurring at 5am body time — a time when cognitive performance is impaired,” he said.
Greater sleep regularity was associated with improved GPAs. Every 10-point increase on the sleep regularity index was linked 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 an indication of other daily habits that hamper with the students’ performance in college.
Increasing contact with daytime light and decreasing exposure to laptops and other light-emitting devices before sleeping at night might improve sleep regularity, they advise.
Sleep specialist Dr Rafael Pelayo of the Stanford Sleep Medicine Centre in California told Reuters Health that while it’s possible some people can tackle sleep irregularity better than others; many students may be underperforming and not realise 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?’”
Usually students say when they go to bed or wake up depends on what day it is. When they’re on different timetables 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 must wake up, and make that your daily wakeup time for the whole week. Do the same for bedtimes by sleeping at the same time every day. “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.”