In search of lost sleep: Secular trends in the sleep time of school-aged children and adolescents

a Health and Use of Time (HUT) Group, University of South Australia, GPO Box 2471, Adelaide SA 5000, Australiab Sansom Institute for Health Research, University of South Australia, GPO Box 2471, Adelaide SA 5000, Australiac School of Health Sciences, University of South Australia, GPO Box 2471, Adelaide SA 5000, AustraliaReceived 7 January 2011. Revised 18 March 2011. Accepted 18 March 2011. Available online 25 May 2011.View full text Sleep deficits are associated with a wide range of detrimental physical and mental health outcomes. There is concern that children are not getting enough sleep, and that sleep duration has been declining. However, evidence is sparse.

A systematic review of world literature was conducted to locate studies reporting the sleep duration of children aged 5–18 years. Monte Carlo simulation was used to generate pseudodata from summary data, which were combined with raw data and analysed by linear regression of sleep duration on year of measurement at the age × sex × day type × country level.

Data were available on 690,747 children from 20 countries, dating from 1905 to 2008. From these data, 641 regressions were derived. The sample-weighted median rate of change was -0.75 min nightly per year, indicating a decrease of more than 1 h per night over the study period. Rates of change were negative across age, sex and day type categories, but varied according to region, with Europe, the USA, Canada and Asia showing decreases and Australia, the UK and Scandinavia showing increases.

Over the last 103 years, there have been consistent rapid declines in the sleep duration of children and adolescents.

prs.rt("abs_end");Sleep duration; Children; Adolescents; Trends

Figures and tables from this article:

Fig. 1. PRISMA flowchart for the search.

View Within ArticleFig. 2. Funnel plots of changes in sleep duration (Y-axis, min/year) against the span of years for each regression, and the total sample size for each regression (X-axes). The dashed line is the sample-weighted median rate of change (-0.75 min/year).

View Within ArticleFig. 3. Box plots showing sample-weighted rates of change for age (Fig. 3a), sex (Fig. 3b) and day type (Fig. 3c) sub-groups. The dashed line is the sample-weighted median rate of change (-0.75 min/year). k = number of regressions assessed; SD = standard deviation; IQR = interquartile range.

View Within ArticleFig. 4. Box plots showing sample-weighted rates of change for different regions. The dashed line is the sample-weighted median rate of change (-0.75 min/year). k = number of regressions assessed; SD = standard deviation; IQR = interquartile range.

View Within ArticleFig. 5. Box plots showing sample-weighted rates of change for different year periods. The dashed line is the sample-weighted median rate of change (-0.75 min/year). k = number of regressions assessed; SD = standard deviation; IQR = interquartile range.

View Within ArticleTable 1. Search strategy used for each database.

View Within ArticleTable 2. Rates of change (minutes per day per year) in sleep duration according to sex, age, day type and geographical location.

Significant differences were found across age groups (with the exception of 13–15 and 16–18 year-old age categories), sexes, regions and between different day types (P < 0.05).k = number of regressions assessed; n = sample size; SD = standard deviation; IQR = interquartile range.

View Within ArticleCopyright © 2011 Elsevier Ltd. All rights reserved.

prs.rt('data_end');

View the original article here

In search of lost sleep: Secular trends in the sleep time of school-aged children and adolescents

a Health and Use of Time (HUT) Group, University of South Australia, GPO Box 2471, Adelaide SA 5000, Australiab Sansom Institute for Health Research, University of South Australia, GPO Box 2471, Adelaide SA 5000, Australiac School of Health Sciences, University of South Australia, GPO Box 2471, Adelaide SA 5000, AustraliaReceived 7 January 2011. Revised 18 March 2011. Accepted 18 March 2011. Available online 25 May 2011.View full text Sleep deficits are associated with a wide range of detrimental physical and mental health outcomes. There is concern that children are not getting enough sleep, and that sleep duration has been declining. However, evidence is sparse.

A systematic review of world literature was conducted to locate studies reporting the sleep duration of children aged 5–18 years. Monte Carlo simulation was used to generate pseudodata from summary data, which were combined with raw data and analysed by linear regression of sleep duration on year of measurement at the age × sex × day type × country level.

Data were available on 690,747 children from 20 countries, dating from 1905 to 2008. From these data, 641 regressions were derived. The sample-weighted median rate of change was -0.75 min nightly per year, indicating a decrease of more than 1 h per night over the study period. Rates of change were negative across age, sex and day type categories, but varied according to region, with Europe, the USA, Canada and Asia showing decreases and Australia, the UK and Scandinavia showing increases.

Over the last 103 years, there have been consistent rapid declines in the sleep duration of children and adolescents.

prs.rt("abs_end");Sleep duration; Children; Adolescents; Trends

Figures and tables from this article:

Fig. 1. PRISMA flowchart for the search.

View Within ArticleFig. 2. Funnel plots of changes in sleep duration (Y-axis, min/year) against the span of years for each regression, and the total sample size for each regression (X-axes). The dashed line is the sample-weighted median rate of change (-0.75 min/year).

View Within ArticleFig. 3. Box plots showing sample-weighted rates of change for age (Fig. 3a), sex (Fig. 3b) and day type (Fig. 3c) sub-groups. The dashed line is the sample-weighted median rate of change (-0.75 min/year). k = number of regressions assessed; SD = standard deviation; IQR = interquartile range.

View Within ArticleFig. 4. Box plots showing sample-weighted rates of change for different regions. The dashed line is the sample-weighted median rate of change (-0.75 min/year). k = number of regressions assessed; SD = standard deviation; IQR = interquartile range.

View Within ArticleFig. 5. Box plots showing sample-weighted rates of change for different year periods. The dashed line is the sample-weighted median rate of change (-0.75 min/year). k = number of regressions assessed; SD = standard deviation; IQR = interquartile range.

View Within ArticleTable 1. Search strategy used for each database.

View Within ArticleTable 2. Rates of change (minutes per day per year) in sleep duration according to sex, age, day type and geographical location.

Significant differences were found across age groups (with the exception of 13–15 and 16–18 year-old age categories), sexes, regions and between different day types (P < 0.05).k = number of regressions assessed; n = sample size; SD = standard deviation; IQR = interquartile range.

View Within ArticleCopyright © 2011 Elsevier Ltd. All rights reserved.

prs.rt('data_end');

View the original article here

Secular trends in adult sleep duration: A systematic review

Little evidence exists to support the common assertion that adult sleep duration has declined. We investigated secular trends in sleep duration over the past 40 years through a systematic review.

Systematic search of 5 electronic databases was conducted to identify repeat cross-sectional studies of sleep duration in community-dwelling adults using comparable sampling frames and measures over time. We also attempted to access unpublished or semi-published data sources in the form of government reports, theses and conference proceedings. No studies were excluded based on language or publication date. The search identified 278 potential reports, from which twelve relevant studies were identified for review.

The 12 studies described data from 15 countries from the 1960s until the 2000s. Self-reported average sleep duration of adults had increased in 7 countries: Bulgaria, Poland, Canada, France, Britain, Korea and the Netherlands (range: 0.1–1.7 min per night each year) and had decreased in 6 countries: Japan, Russia, Finland, Germany, Belgium and Austria (range: 0.1–0.6 min per night each year). Inconsistent results were found for the United States and Sweden.

There has not been a consistent decrease in the self-reported sleep duration of adults from the 1960s to 2000s. However, it is unclear whether the proportions of very short and very long sleepers have increased over the same period, which may be of greater relevance for public health.

Table 1. Literature search strategy and number of results for each database.

View Within ArticleTable 2. Summary of included results by country (some studies have multiple results).

View Within ArticleCopyright © 2011 Elsevier Ltd. All rights reserved.

View the original article here

Secular trends in adult sleep duration: A systematic review

Little evidence exists to support the common assertion that adult sleep duration has declined. We investigated secular trends in sleep duration over the past 40 years through a systematic review.

Systematic search of 5 electronic databases was conducted to identify repeat cross-sectional studies of sleep duration in community-dwelling adults using comparable sampling frames and measures over time. We also attempted to access unpublished or semi-published data sources in the form of government reports, theses and conference proceedings. No studies were excluded based on language or publication date. The search identified 278 potential reports, from which twelve relevant studies were identified for review.

The 12 studies described data from 15 countries from the 1960s until the 2000s. Self-reported average sleep duration of adults had increased in 7 countries: Bulgaria, Poland, Canada, France, Britain, Korea and the Netherlands (range: 0.1–1.7 min per night each year) and had decreased in 6 countries: Japan, Russia, Finland, Germany, Belgium and Austria (range: 0.1–0.6 min per night each year). Inconsistent results were found for the United States and Sweden.

There has not been a consistent decrease in the self-reported sleep duration of adults from the 1960s to 2000s. However, it is unclear whether the proportions of very short and very long sleepers have increased over the same period, which may be of greater relevance for public health.

Table 1. Literature search strategy and number of results for each database.

View Within ArticleTable 2. Summary of included results by country (some studies have multiple results).

View Within ArticleCopyright © 2011 Elsevier Ltd. All rights reserved.

View the original article here

How to Trade Penny Stocks Using Trends and Sectors

Learning how to trade penny stocks for those wishing to use a momentum or swing trading methodology requires diligence and an ever watchful eye on the fickle wants and needs of the market. What may be a blazing hot sector today could be stagnant tomorrow. Investors and traders that execute momentum and swing trades realize that short term gains numbered in days or at the most, a few weeks is desirable.

Penny stocks in the energy sectors and gold sectors are ideal candidates for utilizing this methodology of trading. Spikes in the cost per barrel of oil caused by a geo-political event can result in oil stocks rising as investors flock to these stocks to ride the wave of profitability as oil prices surge. The same goes for gold stocks. As the price of gold per ounce increases because of a dip in the economy or an event rocks the financial world, investors buy into gold stocks to ride the momentum for profit.

During certain times of the year, some stocks are ideal for trading with trends and sectors. Companies that provide goods and services that provide relief during catastrophic events such as hurricanes are excellent choices during the hurricane season that plagues the southeastern United States during the fall months of the year.

Investors and traders that keep their eyes on current trends realize that there is most likely a company trading on either the OTCBB or Pink Sheet stock exchanges that has a product that has the potential to meet the demand. One area that always evokes strong opinions is the stem cell industry. Whenever legislation is before the houses of Congress concerning stem cells, stocks that are associated with stem cell research always surge in anticipation of legislation going forward.

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