A good night’s rest is a pillar of health - read Dr. Mercola’s comprehensive guide to sleep better and fight the sleep problem called insomnia.
Sleep is one of the great mysteries of life. For a long time, it was widely thought that sleep was little more than a waste of time. Modern research, however, has shed much-needed light on the matter, showing sleep is a crucial component of a healthy lifestyle, and that lack of sleep can have far-reaching consequences, affecting everything from mood, creativity and brain detoxification to DNA expression, chronic disease risk — including dementia — and longevity.One of the most radical and recent discoveries revealing the importance of sleep for health is that each and every organ, indeed each cell, has its own biological clock. The 2017 Nobel Prize in Physiology or Medicine was awarded for the discovery of these cellular clocks, all of which work in tandem to control and maintain biological homeostasis, regulating everything from metabolism to psychological functioning.
In your brain is a “master clock” that synchronizes these clocks and your bodily functions to match the 24-hour light and dark cycle.
When you upset your circadian rhythm by not getting enough sleep, the results cascade through your system, raising blood pressure, dysregulating hunger hormones and blood sugar, increasing the expression of genes associated with inflammation, immune excitability, diabetes, cancer risk and stress and much more.
Ideal Sleep Duration for Optimal Health
According to a scientific review of more than 300 studies published between 2004 and 2014 to ascertain how many hours of sleep most people need to maintain their health, a panel of experts came up with the following recommendations.
Sleep Deprivation Takes a Toll on Your Health
In truth, few (if any) facets of your biology are unaffected when you skimp on sleep, as the list of health effects linked to poor sleep or lack of sleep keeps growing with each passing year. For example, poor or insufficient sleep have been linked to:- Impaired memory and reduced ability to learn new things — Due to your hippocampus shutting down, you will experience a 40% deficit in your brain with respect to its ability to make new memories when you’re sleep deprived.
- Reduced ability to perform tasks, resulting in reduced productivity at work and poor grades in school.
- Reduced athletic performance.
- Reduced creativity at work or in other activities.
- Increased risk of neurological problems, ranging from depression to dementia and Alzheimer’s disease — Your blood-brain barrier becomes more permeable with age, allowing more toxins to enter. This, in conjunction with reduced efficiency of the glymphatic system due to lack of sleep, allows for more rapid damage to occur in your brain and this deterioration is thought to play a significant role in the development of Alzheimer’s.
- Increased risk of Type 2 diabetes — In one study, “excessive daytime sleepiness” increased the risk of Type 2 diabetes by 56%.
- Weakened immune function — Research suggests deep sleep strengthens immunological memories of previously encountered pathogens. In this way, your immune system is able to mount a much faster and more effective response when an antigen is encountered a second time.
- Increased risk of obesity — By causing a prediabetic state, lack of sleep increases feelings of hunger, even if you’ve already eaten, which can wreak havoc on your weight.
- Increased risk of cancer — Tumors grow two to three times faster in laboratory animals with severe sleep dysfunctions. The primary mechanism thought to be responsible for this effect is disrupted melatonin production, a hormone with both antioxidant and anticancer activity. Melatonin both inhibits the proliferation of cancer cells and triggers cancer cell apoptosis (self-destruction). It also interferes with the new blood supply tumors require for their rapid growth (angiogenesis).
- Increased risk of high blood pressure, heart attacks and cardiovascular disease — As noted by professor Matthew Walker, Ph.D., founder and director of the University of California Berkeley’s Center for Human Sleep Science and author of the book “Why We Sleep: The New Science of Sleep and Dreams:”
“In the spring when we lose one hour of sleep, we see a subsequent 24 percent increase in heart attacks. In the fall, when we gain one hour of sleep, we see a 21 percent decrease in heart attacks. That is how fragile your body is with even the smallest perturbations of sleep …”
In his book, Walker also cites Japanese research showing male workers who average six hours of sleep per night or less are 400 to 500% more likely to suffer one or more cardiac arrests than those getting more than six hours of sleep each night.
Cycles of Light and Darkness Affect Your Sleep and Health
Maintaining a natural rhythm of exposure to daylight, and darkness at night, is an essential component of sleeping well. As mentioned earlier, the reason light is so important is because it serves as the major synchronizer of the master clock in your brain — the suprachiasmatic nuclei (SCN).Most people in Western societies spend the larger portion of each day indoors, which essentially puts you in a state of “light deficiency,” as the light indoors is about two orders of magnitude lower, in terms of light intensity, than outdoor light.
To maintain healthy master clock timing, it’s important to get bright light exposure during the day. Many indoor environments simply aren’t intense enough to anchor your circadian rhythm. The first 30 to 60 minutes of outdoor light exposure during the morning or mid-day creates about 80% of the anchoring effect.
This means that just going outside for half an hour at lunch time can provide you with the majority of anchoring light you need to maintain a healthy circadian rhythm. Exposure to early morning sunlight can be another important anchor for circadian rhythm syncing.
On the opposite end, you need to avoid bright artificial lighting after sunset, as light will impair your melatonin production. Somewhere between 50 and 1,000 lux is the activation range within which light will begin to suppress melatonin production.
One 2011 study compared daily melatonin profiles in individuals living in room light (<200 lux) versus dim light (<3 lux). Results showed that, compared with dim light, exposure to room light before bedtime suppressed melatonin in 99% of individuals, and shortened the time period when the body has an elevated melatonin level by about 90 minutes.
