Identifying the Best Times for Cognitive Functioning Using New Methods: Matching University Times to Undergraduate Chronotypes

Lockley

et al. 2017

Front. Hum. Neurosci.

Self Cite

While many studies have shown the benefits of later school starts, including better student attendance, higher test scores, and improved sleep duration, few have used starting times later than 9:00 a.m. Here we report on the implementation and impact of a 10 a.m. school start time for 13 to 16-year-old students. A 4-year observational study using a before-after-before (A-B-A) design was carried out in an English state-funded high school. School start times were changed from 8:50 a.m. in study year 0, to 10 a.m. in years 1–2, and then back to 8:50 a.m. in year 3. Measures of student health (absence due to illness) and academic performance (national examination results) were used for all students. Implementing a 10 a.m. start saw a decrease in student illness after 2 years of over 50% (p < 0.0005 and effect size: Cohen's d = 1.07), and reverting to an 8:50 a.m. start reversed this improvement, leading to an increase of 30% in student illness (p < 0.0005 and Cohen's d = 0.47). The 10:00 a.m. start was associated with a 12% increase in the value-added number of students making good academic progress (in standard national examinations) that was significant (<0.0005) and equivalent to 20% of the national benchmark. These results show that changing to a 10:00 a.m. high school start time can greatly reduce illness and improve academic performance. Implementing school start times later than 8:30 a.m., which may address the circadian delay in adolescents' sleep rhythms more effectively for evening chronotypes, appears to have few costs and substantial benefits.

Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Is 8:30 a.m. Still Too Early to Start School? A 10:00 a.m. School Start Time Improves Health and Performance of Students Aged 13–16

Lockley

et al. 2017

Front. Hum. Neurosci.

Self Cite

“…Sleep deprivation can have a negative impact on learning and memory processes, decreasing the ability to encode new memories though LTP and LTM processes, and may disrupt consolidation in sleep. Individuals have distinctive circadian patterns by chronotype that determine the best times for cognitive functions, as shown in optimum times in their 24-h profiles that identify best times (Evans et al, 2017 ). Studies of learning and memory that do not control for circadian variations may be flawed or fail to identify chronotypes as a significant factor in the variations in outcomes.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, changes in light depend only on geophysical location and the pRGC/SCN timing mechanism, leading us to measure biological time as Geophysical Biological Time (GBT). GBT uses only the environmental cues of changing light in a specific geophysical location to calculate biological time and determining optimal timings for human activities (Bass and Lazar, 2016 ; Evans et al, 2017 ). The differences between GBT and UTC can be important, as shown in studies of Time Zone anomalies (Yasseri et al, 2012 ) and Daylight Savings Time (Coren, 1996 ).…”

Section: Circadian Neurosciencementioning

confidence: 99%

“…Projections from our earlier work suggested 11:00 to 11:30. There are two important findings arising from chronotype variations and being at their best measures for each hour: first, any fixed morning start time in the university would lead to some sleep deprivation or disadvantage some chronotype group, and second, no hour in the day for learning would be optimal for all chronotype groups (Evans et al, 2017 ). The conclusion that much later starting times were required in this age range was expected, but the conclusion that there was no single starting time produced optimal times for all chronotypes was not.…”

Section: Circadian Neurosciencementioning

confidence: 99%

See 1 more Smart Citation

Making Memories: Why Time Matters

Evans

2018

Front. Hum. Neurosci.

Self Cite

In the last decade advances in human neuroscience have identified the critical importance of time in creating long-term memories. Circadian neuroscience has established biological time functions via cellular clocks regulated by photosensitive retinal ganglion cells and the suprachiasmatic nuclei. Individuals have different circadian clocks depending on their chronotypes that vary with genetic, age, and sex. In contrast, social time is determined by time zones, daylight savings time, and education and employment hours. Social time and circadian time differences can lead to circadian desynchronization, sleep deprivation, health problems, and poor cognitive performance. Synchronizing social time to circadian biology leads to better health and learning, as demonstrated in adolescent education. In-day making memories of complex bodies of structured information in education is organized in social time and uses many different learning techniques. Research in the neuroscience of long-term memory (LTM) has demonstrated in-day time spaced learning patterns of three repetitions of information separated by two rest periods are effective in making memories in mammals and humans. This time pattern is based on the intracellular processes required in synaptic plasticity. Circadian desynchronization, sleep deprivation, and memory consolidation in sleep are less well-understood, though there has been considerable progress in neuroscience research in the last decade. The interplay of circadian, in-day and sleep neuroscience research are creating an understanding of making memories in the first 24-h that has already led to interventions that can improve health and learning.

Effects of Shift Work on Toxicology and Carcinogenesis

Zarbl

2023

Patty's Toxicology

The existence of biological clocks that control many of our daily activities and physiological functions has always been part of tacit knowledge. Biological clocks tuned to the earth's 24‐h light/dark cycles are a fundamental property of all life on earth. We now understand that essentially every cell in our body has a free‐running molecular clock with an intrinsic periodicity of ∼24 h. These peripheral clocks are synchronized by a central timekeeper in the brain whose periodicity is determined by the amount of light entering the eyes. The central pacemaker coordinates peripheral clocks with the earth's rotation cycle. Social activities, occupations, and environmental exposures (e.g., light pollution, working at night, stress, conflict, illness, social pressures, chemical exposures, noise, and lifestyle) that disrupt biological clocks affect the quality of our sleep, our sense of well‐being, as well as our ability to function, perform tasks and learn. More importantly, chronic circadian disruption negatively impacts our health and susceptibility to chronic diseases and aging. An estimated 20–30% of the modern workforce is employed in jobs that require working night shifts associated with circadian disruption, putting a significant fraction of the workforce at increased risk of poor performance, errors, accidents, and decreased quality of life and health. To address this increasing public health issue, toxicologists, industrial hygienists, and occupational health clinicians must understand mechanisms by which exposures disrupt biological clocks, and use this knowledge to develop and implement targeted preventive, interventions, and mitigation strategies to reduce risks.