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Are you a night owl? Do you work the night shift? Do you have trouble getting to sleep or sleeping through the night? If so, your biggest worry isn't dragging yourself through the next day. You may also be at significantly higher risk of gaining weight, and developing metabolic syndrome and diabetes
In a comprehensive review of sleep and metabolism studies published in The Lancet Diabetes and Endocrinology, German researchers noted that sleep loss has been rising at epidemic rates in our society. The increase parallels the rise in obesity, metabolic syndrome and type 2 diabetes throughout the world. Epidemiological studies clearly point to a link between those conditions and short sleep duration, sleep disturbances and sleeping at the wrong times.
Sleep Loss Increases Risk of Metabolic Syndrome
The researchers noted that data from the Adult Health and Behavior Project registry, including 1,214 Americans aged 30--54 years, showed a clear association between short sleep duration and an increased prevalence of metabolic syndrome.[i]
Metabolic syndrome is usually defined as a cluster of metabolic disturbances including belly fat, impaired glucose metabolism, and high blood pressure. All of those factors increase the risk of cardiovascular disease and mortality.
In the Adult Health study, 22% of participants developed metabolic syndrome. But those who slept only 6-7 hours per night had a 48% increased rate of developing the condition. Those who slept less than 6 hours had an 83% increased rate.
The quality of your sleep also matters. In a study of women aged 46--57 years, those who woke intermittently and were awake cumulatively for a long time during the night had a 40% higher rate of metabolic syndrome.[ii]
And if you work at night, several large cohort studies show you may have increased odds of developing metabolic syndrome. In one study of 1,811 employees of an airline, night shift workers were 2.3 times more likely to have metabolic syndrome than regular daytime workers.[iii]
Lack of Sleep Increases Obesity and Type 2 Diabetes
A meta-analysis of 17 studies with more than 600,000 participants, clearly established a link between short sleep duration and increased bodyweight and obesity.[iv] People who got 5 hours or less of sleep at night had a 55% greater likelihood of developing obesity compared to regular sleepers.
In the first National Health and Nutrition Examination Survey (NHANES I) of 9000 Americans researchers found a strong association between short sleep duration and type 2 diabetes.[v] Participants sleeping less than 5 hours per night had a 57% increased risk for type 2 diabetes.
Another meta-analysis confirmed that having difficulty going to sleep raised diabetes risk by 57%, and difficulty staying asleep through the night raised risk by 84%.[vi]
Lack of sleep seems to impair your body's ability to metabolize sugar. In one study researchers restricted the sleep of 11 healthy young men (aged 18--27 years) to 4 hours for six consecutive nights. Sleep restriction was associated with impaired glucose tolerance and reduced insulin response.[vii]
Less sleep can lead to more eating. In a study in adolescents, those sleeping only 6.3 hours consumed foods higher on the glycemic index, including more sweets and desserts compared to those sleeping 8.9 hours.[viii]
And your sleep habits could be sabotaging your weight loss efforts. In a study published in the Annals of Internal Medicine, dieters who got a full night's sleep lost 55% more body fat than those who cut back on sleep. When dieters got two to three hours less sleep, they felt hungrier and produced higher levels of the hormone ghrelin which triggers hunger, increases fat retention and reduces energy expenditures.
When you sleep also matters. In a study published in the Journal Obesity researchers from Northwestern Medicine found people who go to bed late and sleep late eat more calories in the evening, more fast food, and fewer fruits and vegetables. They also weigh more than people who go to sleep earlier and wake up earlier. The authors found the extra daily calories can mean a weight gain of about two pounds per month.
In the study late sleepers went to sleep at an average time of 3:45 a.m., awoke by 10:45 a.m., ate breakfast at noon, lunch at 2:30 p.m., dinner at 8:15 p.m. and a final meal at 10 p.m. Normal sleepers on average were up by 8 a.m., ate breakfast by 9 a.m., lunch at 1 p.m., dinner at 7 p.m., a last snack at 8:30 p.m. and were asleep by 12:30 a.m.
Insufficient Sleep Raises Risk of Hypertension and Death
In the Nurses Health Studies I and II investigators assessed data from more than 70,000 women. They found those who slept less than 5 hours per night had a 19% increased risk of hypertension compared to those getting 7 hours of shuteye.[ix]
Another meta-analysis of 11 prospective studies concluded the risk of hypertension was also increased 20% by disturbed sleep, and 14% by early-morning awakening.[x]
All of that adds up to a shorter life. A meta-analysis of 16 prospective studies and 1,382,999 participants showed that less than 7 hours of sleep per night was associated with a 12% increased risk of death. But more is not necessarily better. Getting more than 8 hours of sleep per night was associated with a 30% increased risk of death.[xi]
How To Get A Good Night's Sleep
The message from these studies is clear. The quantity and quality of your sleep can powerfully affect your metabolism, your weight, your risk of diabetes and heart disease, as well as your lifespan.
Here are some natural tips for a restful night without prescription sleep aids:
1. Be in bed by 9:30 pm and lights out by 10:30 pm at the latest.
2. Don't drink or eat anything after 7:30 pm so that your sleep is not disturbed by bathroom visits.
3. Avoid caffeine and alcohol before bed.
4. Eat foods rich in natural melatonin.
5. Make your bedroom a sanctuary with no television, computer or briefcase allowed.
6. Keep your bedroom dark to get a better, deeper sleep.
7. Don't overheat your bedroom and open a window for fresh air if possible.
8. Relax for an hour or two before bed without work, computers or TV.
[x] Meng L, Zheng Y, Hui R. The relationship of sleep duration and insomnia to risk of hypertension incidence: a meta-analysis of prospective cohort studies. Hypertens Res Off J Jpn Soc Hypertens 2013; 36: 985-995. PubMed