A pilot study of teenagers in a small private school in the US found that delaying the start of the school day by just half an hour was linked to significant improvements in students’ alertness, mood and health and confirms similar findings by other studies.

You can read about the research, by sleep expert Dr Judy Owens, from Hasbro Children’s Hospital in Rhode Island, in a paper she co-authored that was published online the 7 July issue of the Archives of Pediatrics and Adolescent Medicine. Her co-authors were Katherine Belon, also of Hasbro Children’s Hospital and Dr Patricia Moss, of St. George’s School in Newport, Rhode Island, the independent high school where the pilot study took place.

The fact that many American teenagers get less than their recommended 9 hours sleep is a major public health concern, causing Owens and other experts to suggest schools delay their start time.

Research shows that sleep deprivation impairs mood, attention, memory, control of behavior, and quality of life. It is also linked to lower academic performance, reduction in motivation to learn, an increased risk of weight gain, lower levels of physical activity, and higher use of stimulants.

In a statement Owens, who is also an associate professor at The Warren Alpert Medical School Brown University, explained that adolescents’ biology changes as they develop, resulting in a “phase delay” that alters their circadian rhythm and shifts sleep onset and wake times to later.

“On a practical level, this means that the average adolescent has difficulty falling asleep before 11 pm, so the ideal wake time is around 8 am,” she added.

To prove the point, Owens set out to investigate the impact of delaying the start of the school day from 08.00 am to 08.30 am among 201 teenagers (out of 278 who enrolled) in grades 9 to 12 attending St George’s.

The delay in school start time occured during the winter term, and to avoid extending school finish time, small changes of 5 to 10 minutes were made to the school schedule, across academic and non-academic periods.

Owens analyzed data from a questionnaire that the participants completed before and after the school start time changed.

The retrospective questionnaire was the 8-page Sleep Habits Survey, that has been used in with over 3,000 high school students in Rhode Island and also in other countries. The questionnaire seeks to evaluate sleep and wake behaviors and associated problems, and it also measures sleepiness and depression.

The results showed that:

  • There was a significant 45 minutes average increase in sleep duration on school nights across all grades after the start time changed, and average bedtime advanced by 18 minutes.
  • The percentage of students reporting less than 7 hours sleep went down by 79.4 per cent, and those reporting at least 8 hours sleep went up from 16.4 to 54.7 per cent .
  • However, only 11 per cent of students reported getting the recommended 9 hours or more of sleep.
  • There were significant reductions in numbers of students who reported feeling they “rarely/never” got enough sleep (from 69 to 34 per cent) and also among those who reported “never” being satisfied with their sleep (37 to 9 per cent).
  • There was also a significant drop from 15 to 5 per cent in number of students who reported attending the school health center for “fatigue-related” reasons and the health center itself recorded a 56 per cent reduction in requests for “rest passes”.
  • Students reported improved motivation and reduced daytime sleepiness, fatigue and depressed mood.Teachers reported a 36 per cent reduction in absence and lateness for the first class of the day.

The authors concluded that:

“A modest delay in school start time was associated with significant improvements in measures of adolescent alertness, mood, and health.”

“The results of this study support the potential benefits of adjusting school schedules to adolescents’ sleep needs, circadian rhythm, and developmental stage,” they added.

Owens said that perhaps the most important result was that students “rated themselves as less depressed and more motivated to participate in a variety of activities”.

She also stressed biological changes are not the only factors that impact teenagers’ sleep patterns: environment and lifestyle also play a role, including extracurricular activities, homework and after-school jobs.

These factors contribute to loss of sleep during the week, causing teenagers to “sleep in” at the weekend, which disrupts circadian rhythm even more, impacting daytime alertness.

“It’s not surprising that a large number of studies have now documented that the average adolescent is chronically sleep-deprived and pathologically sleepy,” said Owens.

In an accompanying editorial, Dr Kyla Wahlstrom of the University of Minnesota in St Paul, notes that most of the research to date has been longitudinal research, and while it shows changes to the school day appears to be linked to several beneficial academic effects, such as reduced drop out rates, so far it has not linked it directly to academic performance itself.

Until “direct correlation between later start time and academic achievement on normed tests” is proven, schools are not going to rush to change their school day, commented Wahlstrom.

Owens and colleagues acknowledged that the ongoing debate surrounding later school start time remains a controversial one, and it is important to keep an eye on what happens in schools that have gone down this road.

“Impact of Delaying School Start Time on Adolescent Sleep, Mood, and Behavior.”
Judith A. Owens, Katherine Belon, Patricia Moss.
Arch Pediatr Adolesc Med., Vol. 164 No. 7, July 2010.

Additional source: Hasbro Children’s Hospital.

Written by: Catharine Paddock, PhD