A strict bedtime is just as important as getting enough sleep, new study suggests — and naps don’t help either

Going to bed at the same time each night is just as important for academic and business success as getting a long night’s sleep, new research suggests.

Harvard University researchers found that the benefit of sleeping for seven to nine hours a night can be squandered by not going to sleep at a regular time. And the implication is that a shortage of sleep can be, in part, offset by having a reliable routine.

Erratic patterns, of the kind adopted by young students, knock the body’s circadian rhythm out of sync in a similar way to jet lag.

And, in an additional blow to the student lifestyle, the research suggests that napping to top up on sleep missed, while carousing or cramming for examinations, does not help.

Scientists at Brigham and Women’s Hospital in Harvard monitored 61 undergraduates for a month, measuring the quantity and timings of their sleep. They found those who kept regular patterns performed better academically.

The comparative benefit was similar to that observed between people who get the right amount of time in bed and those who are sleep deprived.

Going to sleep and waking up at approximately the same time is as important as the number of hours one sleeps

Prof. Charles Czeisler, a co-author of the research, said that for the students whose sleep times were inconsistent, classes and exams that were scheduled for 9 a.m. felt like they were at 6 a.m. according to their body clock — a time when performance is impaired. The circadian rhythm is a daily cycle of brain-wave activity, hormone production and cell regeneration that is broadly linked to sleep. It was measured in the Harvard students by monitoring their levels of the melatonin hormone, which induces sleep.

The cycle is heavily influenced by light, and the study authors believe irregular sleepers have a delayed circadian rhythm because they do not get enough natural light during the day and too much artificial light at night.

“Regular sleepers had significantly higher levels during the day, and significantly lower levels than irregular sleepers who slept more during daytime hours and less during the night,” said Prof. Andrew Phillips, who led the research.

“Our results indicate that going to sleep and waking up at approximately the same time is as important as the number of hours one sleeps.”

It is known that short sleep duration is linked to cognitive impairment such as delayed reaction time, as well as early mortality prompted by increased chances of obesity, diabetes, cardiovascular and psychiatric diseases.

But the timing of sleep also matters, with those who work rotating night shifts shown to be at higher risk of heart disease and cancer.

A study in 2013, where participants were forced to camp outdoors for a week without artificial light, found their bodies began to prepare for sleep two hours earlier than usual.

Doctors also believe that the blue light emitted from smartphones, laptops and tablets is one of the leading causes of insomnia because of the role it plays in suppressing melatonin production.