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Many people stay up late and head to bed past midnight for only a few hours of sleep. Maybe you have a habit of catching up on work, reading, or watching T.V. until 1 a.m., having a late night snack before you fall asleep. Or maybe you work the graveyard shift, sitting under bright fluorescent lights and eating a large meal on your break in the middle of the night.
Schedules such as these that disrupt the body’s biological clock can pose significant risks to your health. Research links shift work, disrupted sleep, and eating at night to increased cardiovascular risk, with unusual sleep patterns being one of the little-known causes of high triglycerides.
Shift Work Is Associated with Increased Cardiovascular Risk
There are a multitude of studies showing that shift work is associated with cardiovascular disease.[1,2,] Lack of sleep or sleeping odd hours are also considered an independent risk factor for gaining weight, and shift workers are more likely to have obesity than day workers. But what is the cause of this link between sleep disruption and cardiovascular risk?
Initially, it was thought that shift workers may have higher cardiovascular risk because of poor eating habits, socioeconomic factors, or the stress of a difficult schedule. However, recent research correcting for these factors has found that the link may actually be due to disruptions in sleep cycles, causing an alteration in the body’s biological clock.
The Importance of Our Biological Clock
The circadian rhythm regulates our 24-hour sleep-wake cycle. Although most people associate the body clock with a part of the brain that regulates when we sleep, all the cells in our body are actually in tune with this 24-hour cycle. Our circadian rhythm affects many metabolic processes, and many of the genes that regulate our circadian rhythm also regulate the oscillating levels of lipids in our blood. Circadian rhythms control lipid and carbohydrate balance to optimize energy storage for use throughout the day.
Studies have shown that eating out of sync with our normal rhythm, like at night, changes the way our circadian rhythm regulates metabolism. Lipid metabolism, which is reflected in triglyceride and cholesterol levels, is one of the processes that can get out of balance when we sleep and eat on an irregular schedule.
Disrupting Your Sleep Cycle Can Be Part of What Causes High Triglycerides
Studies in shift workers provide substantial evidence for the link between disrupted sleep cycles and elevated triglyceride levels, even after adjusting for other factors such as dietary intake.[1,4,9] Shift workers also have higher LDL cholesterol levels, another risk factor for cardiovascular disease.
Laboratory studies suggest that circadian rhythms and feeding time both influence levels of triglycerides, and that disruption in certain circadian genes such as CLOCK can cause abnormal triglyceride levels in mice.
How Can You Reduce Your Own Cardiovascular Risk?
Although the theory has not been fully tested, researchers think that improving sleep habits could help reverse conditions influenced by disrupted sleep schedules. If you can, try to maintain a regular sleep schedule. Sleep and wake at a reasonable time, making sure that you avoid light exposure at night. Avoid eating at night as well, as eating at a point in the 24-hour cycle when your body does not expect food will result in increased triglycerides and cholesterol.
If your job requires you to work at night or you have an ever-changing schedule with odd hours, be sure that you are monitoring your triglyceride levels. Catching rising triglyceride levels early can help you to make the lifestyle changes necessary to reduce your cardiovascular disease risk. Increasing dietary fiber, exercising more, and taking an omega-3 fatty acid supplement can all help. If you find that you do have high triglycerides, check out my blog on how eating cranberries can lower triglycerides.
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This post originally appeared in 2014 and is regularly updated.