New Sleep Time Recommendations
Getting a good night’s sleep helps repair the body and promotes health and well-being. Too little sleep (less than 5-6 hours) may quadruple our susceptibility to catching a cold, for example (1). And both too short a sleep time – as well as sleeping too long – have been linked to an increased risk of stroke (2). So how much sleep time should we aim for?
In February of this year, the National Sleep Foundation (NSF) provided some guidance on this question when it issued new recommendations for appropriate sleep times by age groups (shown on page 2) (3). The NSF sleep time ranges are defined as “recommended”, “not recommended” or, acknowledging that individuals can vary in how much sleep they need, “may be appropriate for some”.
“This is the first time that any professional organization has developed age-specific recommended sleep durations based on a rigorous, systematic review of the world scientific literature relating sleep duration to health, performance and safety,” according to Charles A. Czeisler, PhD, MD, NSF’s chairman of the board and a sleep expert at Harvard Medical School. The NSF convened a panel of experts from multiple disciplines – sleep, anatomy and physiology, as well as pediatrics, neurology, gerontology and gynecology – to reach a consensus on the new recommendations.
Not getting enough sleep – poor quality as well as too few hours – can cause more than foggy thinking, a grumpy disposition, and poor decision-making. Continual lack of adequate sleep can lower the body’s defenses and increase the risk of developing a number of chronic illnesses. According to Harvard’s sleep information website (4), studies have found that getting less than 5 hours of sleep nightly increases the risk of death from all causes by 15%.
Lack of Sleep Can Contribute to Weight Gain
Along with too little physical activity and overeating, sleep is also being considered as a potential risk factor for obesity. Studies have shown, for example, that people who usually sleep less than 6 hours nightly are much more likely to have a higher than average body mass index (BMI), while those sleeping 8 hours per night have the lowest BMI.
According to the Harvard site, the body secretes hormones that help control appetite, energy metabolism, and glucose processing during sleeping hours. Obtaining too little sleep can upset the balance of these and other hormones.
Poor sleep, for example, is associated with increases in insulin secretion and the production of cortisol (the “stress” hormone). It’s also associated with lower levels of the hormone leptin that signals the brain that we’ve eaten enough food, and higher levels of the appetite stimulant ghrelin.
These changes may result in food cravings, and the likelihood of eating more sweets for an energy boost. To top it off, inadequate sleep can leave us too tired to exercise and use up the extra calories consumed.
What We Eat May Influence Sleep
If lack of sleep can affect our eating behaviors, our food choices may also influence sleep. Consuming certain types of foods which impact the availability of the amino acid tryptophan as well as the production of the neurotransmitters serotonin and the “sleep hormone” melatonin may aid in promoting sleep (5).
Promote sleep by choosing complex carbohydrates (whole grain breads and pastas, brown rice), while avoiding sugary foods, which may reduce serotonin levels. Lean proteins like low-fat cheese, chicken and fish are high in tryptophan, which tends to increase serotonin levels. The caveat here is to avoid deep-fried fish and chicken as they can take longer to digest and may keep you awake.
Finally, for a host of tips on how to get a better night’s sleep, visit the National Sleep Foundations website (sleepfoundation.org).
National Sleep Foundation’s Sleep Duration Recommendations*
Recommended Hours of Sleep
May be appropriate
10 to 13
8 to 9
Less than 8
More than 14
9 to 11
7 to 8
Less than 7
More than 12
8 to 10
Less than 7
More than 11
7 to 9
10 to 11
Less than 6
More than 11
Less than 6
More than 10
65 years & older
7 to 8
5 to 6
Less than 5
More than 9
* Courtesy of the National Sleep Foundation; recommendations for infants and children younger than 3 years are omitted.
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