Research Again Confirms Links Between Poor Sleep, Weight Gain, and Cancer

Sleep deprivation is such a pervasive condition in these days of artificial lights and non-stop entertainment, that you might not even realize you’re not getting enough sleep. It’s important to recognize that sleep is an absolutely crucial component of optimal health and disease prevention.

For example, the link between impaired sleep and cancer has been repeatedly confirmed. Tumors grow two to three times faster in laboratory animals with severe sleep dysfunctions, primarily due to disrupted melatonin production.

Melatonin inhibits the proliferation of a wide range of cancer cell types, as well as triggering cancer cell apoptosis (self-destruction). The hormone also interferes with the new blood supply tumors required for their rapid growth (angiogenesis).

Poor sleep is also associated with an increased risk of insulin resistance and weight gain—two additional factors that also play an important role in cancer development.

Less Sleep = Higher Risk of Cancer

Most recently, a study published in the journal Cancer, Epidemiology, Biomarkers & Prevention1 found that men who had trouble sleeping were twice as likely to develop prostate cancer compared to those who slept well. According to the featured article:2

“This association was even stronger in cases of advanced prostate cancer, and the risk increased relative to the severity of the sleep problems… The lead researcher, Lara Sigurdardottir, Ph.D., expects that, ‘If our results are confirmed in future studies, sleep may become a potential target for intervention to reduce the risk of prostate cancer.”

Another recent study3 found that insufficient sleep may be a contributing factor in both the recurrence of breast cancer, and more aggressive forms of breast cancer among post-menopausal women. According to the study’s co-author Dr. Li Li:4

“Short sleep duration is a public health hazard leading not only to obesity, diabetes and heart disease, but also cancer… Effective intervention to increase duration of sleep and improve quality of sleep could be an under-appreciated avenue for reducing the risk of developing more aggressive breast cancers and recurrence.”

Sleeping less than six hours per night has also been implicated as a risk factor for colorectal adenomas, which may develop into cancer if left untreated. In fact, those who slept less than six hours a night were found to have a 50 percent increased risk compared to those who got seven hours or more of sleep per night.5

Insulin resistance and disrupted melatonin production are two potent mechanisms through which chronic sleep problems affect your cancer risk. The fact that poor sleep can have such a dramatic impact on insulin resistance is why I keep repeating that you simply cannot be optimally healthy unless you also sleep well—even if you eat right and exercise…

Insulin Resistance Drives Both Weight Gain and Cancer

In one 2005 study6 aptly titled: “Sleep loss: a novel risk factor for insulin resistance and Type 2 diabetes,” the authors note that “sleep exerts marked modulatory effects on glucose metabolism.” Lack of sleep also decreases levels of the fat regulating hormone leptin while increasing the hunger hormone ghrelin. The resulting increase in hunger and appetite can easily lead to overeating and weight gain.

According to a recent study in the journal Sleep,7 later bedtimes correlate to greater weight gain even in healthy, non-obese people. Late-night snacking further increases that risk, which shouldn’t come as a great surprise. In fact, avoiding food at least three hours prior to bedtime is one of my standard recommendations as it helps to make sure that your body is burning fat as its primary fuel which will keep you lean. As reported in Medical News Today:8

“Andrea Spaeth and team had one group of participants sleeping just from 4 a.m. to 8 a.m. each night for five nights running, and compared them to a control group who were in bed from 10 p.m. to 8 a.m. The investigators found that those who slept much less consumed more food, and therefore calories, compared to the normal-hours sleepers… Lead author, Andrea Spaeth… said:

‘Although previous epidemiological studies have suggested an association between short sleep duration and weight gain/obesity, we were surprised to observe significant weight gain during an in-laboratory study.'”

The link between insulin resistance/weight gain and cancer may be of particular concern for women… Breast cancer is the most common cancer in women, and obese women are thought to be up to 60 percent more likely to develop cancer than those of normal-weight. The reason for this increased risk is because many breast cancers are fueled by estrogen, a hormone produced in your fat tissue. So the more body fat you have, the more estrogen you’re likely to produce.

How Working the Night Shift May Affect Your Health

Confirming the need for regular sleep during night-time hours, researchers have also noted a link between night shift workers and higher rates of breast, prostate, colorectal cancer, and non-Hodgkin’s lymphoma. Working the night shift also raises your risk of diabetes and obesity.

A Danish study published in the journal Occupational and Environmental Medicine,9 found that women who worked night shifts were significantly more likely to develop breast cancer compared to those who did not work nights. After taking confounding effects into account, such as use of birth control pills, childbirth, hormone replacement therapy, age, and sunbathing, women who worked nights had an overall 40 percent higher risk of breast cancer. As reported by Time Magazine last year:10

“The effect was cumulative: women who worked at least three night shifts a week for six years had twice the risk of breast cancer as those who worked one to two night shifts a week. Most surprising, though, was the fact that women who worked night shifts and described themselves as being ‘morning’ people — that is, they preferred to wake up early, rather than stay up late at night — had a four times higher risk of breast cancer than women who worked during the day.”

Interestingly, this study was also able to discount vitamin D deficiency as a culprit, as night shift workers were found to have greater levels of sun exposure compared to those working indoors during the day. This suggests that hormone disruptions (such as the insulin, leptin, ghrelin and melatonin disruptions discussed above) play a key role in cancer development that vitamin D alone cannot counteract. So again, a healthy lifestyle simply isn’t complete without enough proper sleep.

What You Need to Know About Sleeping Pills

According to a recent report by The Sleep Council,11 nearly half of those polled responded that stress and worry keep them tossing and turning at night, and nearly seven million Americans resort to sleeping pills in order to get some rest. While it may be tempting to look for a pill to quickly help you sleep, they will not address any of the underlying causes of insomnia.

In fact, researchers have repeatedly shown that sleeping pills don’t work, but your brain is being tricked into thinking they do… In one meta-analytic study, they found that, on average, sleeping pills help people fall asleep approximately 10 minutes sooner. From a biomedical perspective, this is an insignificant improvement.

On average, sleeping pills increase total sleep time by about 15-20 minutes. But here is the catch: This study also discovered that while most sleeping pills created poor, fragmented sleep, they also created amnesia, so upon waking, the participants could not recall how poorly they’d actually slept! Worse yet, sleeping pills have also been linked to a wide variety of health hazards, including a nearly four-fold increase in the risk of death, along with a 35 percent increased risk of cancer.

Additionally, most people do not realize that over-the-counter (OTC) sleeping pills — can have a half life of about 18 hours. So, if you take them every night, you’re basically sedated much of the time. Not surprisingly, they’re associated with cognitive deficits in the morning. Trust me, there are far better, safer and more effective ways to get a good night’s sleep…

Tips to Help You Sleep Better

There are many variables that impact how well you sleep. I suggest you read through my full set of 33 healthy sleep guidelines for all of the details, but to start, making some adjustments to your sleeping area can go a long way to ensure uninterrupted, restful sleep.

    1. Cover your windows with blackout shades or drapes to ensure complete darkness. Even the tiniest bit of light in the room can disrupt your pineal gland’s production of melatonin and the melatonin precursor serotonin, thereby disrupting your sleep cycle.

So close your bedroom door, get rid of night-lights, and refrain from turning on any light during the night, even when getting up to go to the bathroom. If you have to use a light, install so-called “low blue” light bulbs in your bedroom and bathroom. These emit light that will not suppress melatonin production.

  1. Keep the temperature in your bedroom at or below 70 degrees F (21 degrees Celsius). Many people keep their homes and particularly their upstairs bedrooms too warm. Studies show that the optimal room temperature for sleep is quite cool, between 60 to 68 degrees F (15.5 to 20°C). Keeping your room cooler or hotter can lead to restless sleep.
  2. Check your bedroom for electro-magnetic fields (EMFs). These can also disrupt your pineal gland’s production of melatonin and serotonin, and may have other negative effects as well. To do this, you need a gauss meter. You can find various models online, starting around $50 to $200. Some experts even recommend pulling your circuit breaker before bed to kill all power in your house.
  3. Move alarm clocks and other electrical devices away from your head. If these devices must be used, keep them as far away from your bed as possible, preferably at least three feet.
  4. Reduce use of light-emitting technology, such as your TV, iPad, and computer, before going to bed. These emit the type of light that will suppress melatonin production, which in turn will hamper your ability to fall asleep, as well as increase your cancer risk (melatonin helps to suppress harmful free radicals in your body and slows the production of estrogen, which can contribute to cancer). Ideally, you’ll want to turn all such light-emitting gadgets off at least one hour prior to bedtime.

As previously discussed by Dr. Rubin Naiman, a leader in integrative medicine approaches to sleep and dreams, sleep is the outcome of an interaction between two variables, namely sleepiness and what he refers to as “noise.” This is any kind of stimulation that inhibits or disrupts sleep. In order to get a good night’s sleep, you want your sleepiness level to be high, and the “noise” level to be low. Under normal conditions, your sleepiness should gradually increase throughout the day and evening, peaking just before you go to bed at night. However, if noise is conceptually greater than your level of sleepiness, you will not be able to fall asleep.

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Improving Your Sleep Hygiene Pays Off in Health Dividends

As you can see, you can have the healthiest diet on the planet, doing vegetable juicing and using fermented veggies, be as fit as an Olympic decathlete, be emotionally balanced, but if you aren’t sleeping well it is just a matter of time before it will adversely, and potentially seriously, affect your health. Sure, we all lose sleep here and there, and your body can adjust for temporary shortcomings, but if you develop a chronic pattern of sleeping less than five or six hours a night, then you’re increasing your risk of a number of health conditions, including insulin resistance and diabetes, weight gain, heart disease, and cancer.

To make your bedroom into a suitable sleep sanctuary, begin by making sure it’s pitch-black, cool, and quiet. Remember, even the tiniest bit of light can disrupt your pineal gland’s production of melatonin and serotonin. For this reason, I highly recommend adding room-darkening blinds or drapes to your bedroom, or if this is not possible wear an eye mask to block out any stray light.

If you’re even slightly sleep deprived I encourage you to implement some of these tips tonight, as high-quality sleep is one of the most important factors in your health and quality of life.

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Copyright © 2013 Dr. Joseph Mercola

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