Q: In this interview we will discuss five things that harm the brain. We’ll start with adequate sleep. As a culture are we sleeping less than we used to?

1. Inadequate Sleep

PVH: Yes. The average adult sleeps at least an hour less a night than 100 years ago, and  about 30 minutes less a night than a decade ago. There are multiple causes of this decline in sleep time, but one factor may be taking digital media to bed. There are studies showing that using digital devices just before sleep can cause poor quality sleep.

Q: How would you define adequate sleep?

PVH: For the average adult it’s between 7 and 8 hours a night, and what you do every night or most nights is more important than what you do occasionally. If don’t have a choice and need to stay up late for a special event or because you’re on a trip, your body will easily adjust to that. It’s your typical bedtime that’s important, and also your usual time of getting up. That’s what your body clock uses as its cues to establish your unique 24-hour body cycle.

Q: How does inadequate sleep harm the brain?

PVH: Inadequate sleep has many bad effects. It impairs the brain’s cognitive function the following day. Also, the brain repairs itself during sleep — you might call it “janitorial” time for the brain. There are specific mechanisms within the brain that go into effect during sleep and clean up the debris created by the brain’s activity and cellular metabolism. The precise mechanism of this nightly repair was only recently discovered.

Inadequate sleep robs the brain of some of this janitorial time. If the debris is not cleaned up adequately, it can cause early cognitive changes such as loss of memory or even serious neuro-degenerative disorders such as Alzheimer’s, Parkinson’s, and Multiple Sclerosis.  In general, for anybody with a neuro-degenerative disorder, adequate sleep is especially important for the brain’s janitorial functions.

Sleep is also the time when our brain consolidates memory from the previous day. If we’ve learned new information during the day, the neural consolidation process, which enables us to remember that information, takes place during sleep. Sleep also resets the brain so that we can learn new information the next day. This is why students, especially, need to get adequate sleep.

Q: Do people need more or less sleep time depending upon age?

PVH: Children and teens tend to need more than average sleep because their brains are still developing. Normal healthy adults, well into their 50s, will usually need average sleep amounts. But sleep efficiency tends to go down in people over 60 even if they’ve been accustomed to normal sleep previously. To get adequate amounts of sleep, an older person often needs to sleep more hours.

Q: Does taking naps help?

PVH: Yes, but only if the nap doesn’t interfere with a person’s ability to fall asleep at night. What helps us fall asleep at night is the build up of a certain metabolite in the spinal fluid. Taking a nap decreases the amount of that metabolite so that when bedtime comes a person may not have the usual urge to go to sleep. If an older person is having trouble getting adequate sleep, the important thing is to go to bed earlier.

Q: Besides impaired cognitive functioning, what are the warning signs of lack of sleep?

PVH: Feeling tired and less energetic is a nearly universal sign. There can also be an effect on mood, expressed as anxiety or depression.  Increased appetite and tendency to be sedentary are also common, as well as  decreased immune system function and a greater chance of getting sick.

Q: Does meditation decrease the need for sleep?

PVH: In my clinical experience, I’ve seen that most people who meditate regularly need less sleep, anywhere from 20 minutes to an hour less a day. However, for those with a neuro-degenerative disorder, more sleep is necessary even if they meditate regularly.

2. Sedentary Behavior

Q: I understand that sedentary behavior is also harmful to the brain?

PVH: In the medical literature, sedentary behavior and lack of regular exercise is the new epidemic in our culture because so many bodily processes are affected. In addition to all the positive cardiovascular benefits of physical exercise, regular exercise releases specific brain hormones that are especially beneficial for the brain. The studies show that people who regularly engage in moderate activity have less cognitive decline, and also less depression and anxiety.

Q: How do you define “moderate activity?”

PVH: In the medical literature, “moderate activity” can be something a simple as walking briskly, as if you are late for an appointment. Strenuous exercise is not necessary.

Q: Are frequent short periods of exercise as effective as a single long session?

PVH: Yes. Walking is an excellent exercise and it can be broken up into five minute segments during the day. To give yourself more exercise, you can simply go up and down stairs periodically.

Q: For how long each day should a person in relatively good health exercise?

PVH: Up to about an hour a day of exercise will produce positive benefits for the brain and the body overall. A good minimum is 20 minutes to half an hour, but there will be extra benefit if you exercise more, up to an hour. After an hour, there’s still a benefit, but you begin to experience diminishing returns.

Q: Many people are using stand-up desks at work and at home to insure that they move around enough when they work. Are these desks helpful?

PVH: Yes. With a standup desk you do in fact tend to move around much more and that’s beneficial. You’re constantly moving and shifting your weight, and using all the muscles in your legs. Your leg muscles are stronger at the end of the day and you also burn more calories.

Q: But, as you said, a person can get those same exercise benefits by getting up and walking around regularly?

PVH: Yes, of course. Another reason to get up and walk around is that you’ll breathe more. People with sleep apnea stop breathing at night and their brains are deprived of oxygen.

Surprisingly, recent studies show that, when typing at a computer, people tend to hold their breath. We’re finding that under-breathing can have negative cognitive effects such as poorer memory and slower thinking. We believe this type of abnormal breathing is actually a kind of “concentration apnea,” because whenever we focus on something, we naturally tend to hold our breath.

3. Harmful Substances

Q: Today, in our culture, what are the most commonly used harmful substances?

PVH: The most frequently used harmful substance in our culture is alcohol. Even in very low doses, alcohol is damaging to the brain and nervous system. One study of men showed that drinking more than two and half alcoholic drinks a day for six years impaired their memory and other cognitive functions. However, other studies have shown that drinking two alcoholic drinks or less a day is probably safe for the brain.

I try to keep this simple for my patients. I tell them that two small glasses of wine a day, or two beers a day, are likely safe — but absolutely no binge drinking. Even if someone drinks one beer a day for 12 days but then, every other weekend, drinks a 12-pack of beer, drinking that extra amount is very harmful to the brain.

Q: The physiological effects of over-drinking are well known. Are the effects of excessive drinking on the brain new to science?

PVH: Yes, and also the amounts one can safely drink. As recently as five years ago there were still questions about the maximum one could drink without it being detrimental to the brain. Now we have the answer.

Q: What other substances besides alcohol are harmful to the brain?

PVH: At every medical visit at our clinic, we always ask about smoking.  Nicotine is an intoxicant, which interferes with sleep and causes other problems including depression and decreased tolerance to pain.

But the main harm of cigarette smoking is that it introduces carbon monoxide into the bloodstream. Carbon monoxide binds to hemoglobin much more tightly than does normal oxygen, and thereby robs the blood of the ability to supply oxygen to the brain. Every year, particularly during cold weather, people die from carbon monoxide poisoning from using heaters or other propane or natural gas powered appliances indoors without adequate ventilation.

When you inhale cigarette smoke you’re inhaling tremendous amounts of carbon monoxide and essentially robbing your brain of oxygen. Prolonged exposure can cause damage to the brain and central nervous system, resulting in memory loss, poor concentration, and other neurological defects.

Q:  Are the effects smoking cannabis the same?

PVH: Yes, but cannabis has such harmful effects on the developing brain and nervous system that no one should use it until their mid-20s. If there’s heavy cannabis use in the teen years or early 20s, while the brain is developing, it predisposes a person to cognitive and mood problems later in life. One should not even use it once a week during these developmental years.

In the last ten years, as people have become more educated to the harmful effects of drug use, drug use by young adults and teens has decreased slightly. However, a recent study showed surprisingly that drug use (alcohol, cannabis, cocaine and opiates) is increasing in adults over 50.

Q: How are they using these drugs?

PVH: Both recreationally and to self-medicate. If someone is feeling anxious, stressed, or has physical pain they’ll “medicate” themselves with any one of these drugs.

Q: Including opiates?

PVH: Yes, unfortunately, opiates (Vicodin, for example) are available on the street and they’re cheap. At very low levels opiates don’t have much effect on brain function, but when taken in higher doses, cognitive function definitely gets impaired. And if people have a tendency toward depression or bipolar disorder, the opiates can make them unstable.

Q: Is there any way to mitigate the harm to the brain caused by these drugs?

PVH: Yes, limiting the use of such drugs is a good first step.  There are a number of ways to help your brain recover: a regular exercise program; a diet with foods supportive of good brain health; and adequate amounts of sleep. But the most important thing is meditation. Meditation dramatically improves brain function. With only about fifteen minutes of meditation a day, people begin to see positive cognitive benefits.

Q: We’ve been discussing substances that harm the brain by affecting cognitive function or mood. Can you explain the difference between cognitive function and mood, as they relate to the brain?

PVH: They’re different subcategories of brain function and involve different areas of the brain. Cognitive function includes your ability to remember, to stay focused on a task, to do an arithmetical problem, and to understand what a saying like a “stitch in time, saves nine” means. Someone whose higher cognitive functions have been damaged would take that last statement literally rather than as a reminder to think preventively.

Medically, when we talk about mood, we mean depression, anxiety, and mood instability, and we consider that a separate category. But there’s often quite a bit of overlap between cognitive function and mood.  When there’s decreased cognitive function as a result of brain damage, people often get depression as well. But each type of damage can also be triggered separately.

4. High Blood Sugar

Q: Is it correct that eating foods that raise our blood sugar also can be harmful to the brain?

PVH: Yes. We live in a culture where eating far too much sugar is very easy to do– there’s sugar in most processed foods. High blood sugar levels actually causes abnormal blood flow patterns in the brain. Excessive consumption of sugar can also cause oxidative stress to the brain, which is very harmful.

Q: What is oxidative stress?

PVH: Oxidative stress is a phenomenon in which cells and tissues become damaged by unstable molecules called free radicals that harm other molecules in domino-like chain reactions. Oxidative stress damages all aspects of a human cell, including DNA.

Q: What are some of the signs or symptoms of oxidative stress?

PVH: Simply put, your brain will underperform.  Slower thinking, poor concentration, and poor memory would all be good examples.

Q: Is high blood sugar harmful to both cognitive function and mood?

PVH: Yes. Even modest elevations in blood sugar will affect cognitive function and mood. If a patient with diabetes tells me his or her memory has been terrible recently, I test their blood sugar levels, and usually I find that the levels are  quite elevated and that is the problem. Or if that same person comes into the clinic another time sobbing and upset, I again look at blood sugar levels. Once I adjust the diabetes medication, the depression lifts and the mood returns to normal as the blood sugar normalizes.

Q: What are some of the worst foods and drinks for high blood sugar?

PVH: Most junk foods, because they contain large amounts of sugar; sugar-laden drinks in general – colas, sodas, and also alcohol (because it’s also a simple carbohydrate like sugar). Fruit juices in excess are also a risk. Small amounts of fruit juice with a meal are fine, but not a big 8oz glass of apple juice, which is the equivalent of about five whole apples.

Q: Is high blood sugar a problem only for people diagnosed as diabetics?

PVH: No. For every person who has type 2 diabetes, there are probably five people in a pre-diabetic state. People who are pre-diabetic don’t need to be on medication, but as their blood sugar level creeps up, their pre-disposition toward having cognitive problems and depression also goes up.  For diabetics and pre-diabetics, both diet and exercise are important because both are very effective in reducing blood sugar.

5. Brain Trauma

Q: Let’s take a look at brain trauma. What exactly is brain trauma?

PVH: Ten years ago when we talked about traumatic brain injury, the focus was on people who’d had skull fractures from car accidents or severe injuries from slipping and hitting their heads on the ice or other hard surface.

Nowadays the focus is on much lower levels of head trauma, generally referred to as “concussions.” An example: The person is briefly knocked out. Afterwards he’s disoriented, seeing stars, and not talking normally. That describes somebody who’s had a significant but minor concussive trauma: we call that simply “a concussion.” We’ve known for about a decade that a concussion affects cognitive function for weeks afterward. It’s literally a brain bruise, and you can see it on an MRI.

We’re realizing now that professional football players who’ve had a lot of head trauma from high speed collisions, often become depressed and even suicidal in their 50s and 60s. Their cognitive function also goes down.

The most recent research has been on minor brain injuries, which are harder to classify, at the time of impact because there so few symptoms, but which are also significant. For example, a high school football player takes a hard hit in a football game, perhaps sees stars for a moment, but is not disoriented or confused afterwards. With some of our better imaging techniques, we’re discovering that these minor hits also cause traumatic injury to the brain, and can have a significant cumulative effect. These are classified as “sub-concussive” traumatic brain injuries.

As people learn that even minor collisions can injure the brain, we’re seeing a decrease in interest in high school football programs in the United States. There’s been considerable media publicity about traumatic brain injury, which the medical profession is taking very seriously. We’re seeing an increase in research for new ways of protecting people from cognitive decline and mood disorders resulting from traumatic brain injuries.

In our society overall, I would say that we’re seeing not only increased awareness of traumatic brain injury, but also of the many other things that have the potential to cause serious harm to the brain. There is also greater interest in finding ways to combat these problems.

Peter Van Houten lives at Ananda Village and is the founder and Medical Director of Sierra Family Medical Clinic near Ananda Village. He frequently lectures and writes on the brain and other "yoga and science" topics.


  1. Yes, yes yes! Thank you for sharing these truth. With diabetes at pandemic levels, this is very helpful! Many blessings, with Love.

  2. Thank you for your wonderful article. I work in the assisted living field with dementia residents. The information was most helpful. Blessings.

  3. Very interesting, I enjoyed the details. The warning on cannabis use in teenagers, etc. with developing brains is intriguing. Gracias, -JB

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