Meditation Part 2 – Effects on physiology

Next up in the ongoing feature series on meditation is a showcase of the many effects meditation has on our physiology (read part 1, the introduction, here).

Reducing blood pressure

Overwhelming evidence shows us that regular mediation can reduce blood pressure. One recent study showed that, in a sample of nursing students in China, those that practised mindfulness meditation for just 30 minutes over 7 days showed reduced systolic blood pressure (systolic blood pressure is the maximum pressure on your blood vessels while your heart is beating, and diastolic is the minimum pressure in between the heartbeats. High pressure for either is bad). This is one of many studies showing similar results on blood pressure (see a meta-analysis here), and a recent review article has suggested that although meditation’s effects on blood pressure are small compared to some drug therapies, it is still clinically meaningful, and can be used very successfully in conjunction with medication.

Effects on the immune system and inflammation

Inflammation is the immune system’s response to a pathogen (like a virus or bacteria) or injury and the purpose is to protect and heal the body from whatever is invading or damaging it. Acute (short-term) inflammation is a good thing – it keeps us from dying from wounds or letting the flu take over our body and destroy it. Chronic inflammation, on the other hand, is not so good. It can lead to lots of nasty things like heart disease, obesity, and general poor health. And it appears that any type of stress (not just wounds and viruses, but also psychological stress!) can lead to chronic inflammation. The effects of meditation on inflammation in the body is a new area of research and it is very exciting. I want to share a brand spanking new paper that’s just come out in Brain, Behavior and Immunity that looked at levels of inflammation in people before and after they’d taken part in an 8-week mindfulness meditation course. They found that the body’s inflammatory response to a psychological stress test decreased after the meditation course compared to before. What’s really interesting about this study is that the levels of cortisol (a stress hormone) in response to the stress test did not change. So the body was still signalling that it was stressed – but the meditation seemed to have an effect on how the immune system then responded to that stress.

Another earlier study from Richard Davidson‘s lab (yay!) showed that participants that had done that same 8-week meditation course produced a better immune response to a flu vaccine compared to participants that had not done the course. This evidence is great news for meditation as a possible treatment in inflammatory illnesses like heart disease, as I’ll explore in a later instalment.

Changes in brain activity

Photo: © Felixcasio | Stock Free Images

Photo: © Felixcasio | Stock Free Images

Our brains are always active with electrical impulses, however, the frequencies of our brain “waves” change depending on what kind of state of awareness we are in. Electroencephalography, or EEG, is a method that measures the electrical signals that our neurons create, and the oscillations in the EEG signals show different frequency ranges, i.e., different rates of activity measured in Hz. Neuroscientists separate these frequency ranges into several different categories: delta, the slowest ones that are usually present when we are asleep, theta, present in drowsiness, alpha, present when eyes are closed and indicating relaxation and reflection, and the fastest, beta, present in active attention. The frequency band that appears to be present during meditation is alpha, which is about 8-13 Hz. A recent Japanese study showed that something called Tanden breathing in Zen meditation, which is abdominal breathing, increased the amount of alpha brain activity. This study also showed that the increased alpha activity was associated with increases in serotonin in the blood, which is a neurotransmitter often associated with positive mood (and deficiencies seem to be related to depression). Other research shows that blood flow to certain parts of the brain increases during meditation.

Not only does brain activity appear to change while someone is meditating, but over time, regular meditation may actually change the brain itself. For example, long-term, regular meditators seem to have bigger hippocampi, which is the area of the brain responsible for memory (but also implicated in being able to regulate our emotions). Regular meditators (compared to people who have never meditated regularly) also show increased blood flow to several important areas in the brain, even when they are not meditating, as shown in this study. And you may not have to be meditating for years and years like an old, wizened monk to see these sorts of effects: one study looked at a group of adults that had never done meditation before and examined brain structure using MRI before and after an 8-week mindfulness meditation program. After the meditation program, the participants showed an increase in grey matter in lots of really important areas of the brain, including those responsible for learning, memory, and emotion control. You may not even need that long – another study showed that only 11 hours of training in something called integrative body–mind training (IBMT, a type of meditation from traditional Chinese medicine) can increase white matter (the connections between different parts of the brain) in areas responsible for self-regulation.

As you can imagine, changes in the brain, along with the other physiological changes mentioned, could have enormous effects on psychological well-being and stress levels. The relationship between meditation and psychological processes, including using meditation as a treatment for some mental illnesses, will be covered in the next part of the meditation feature series.

Meditation Part 1  |  Meditation Part 2  |  Meditation Part 3  |  Meditation Part 4


5 thoughts on “Meditation Part 2 – Effects on physiology

  1. This is really fascinating research. It’s interesting that meditation didn’t actually lower cortisol, but altered the way the body reacted to the stress. It’s really interesting to watch scientific medicine arrive at the same theories put forward by eastern philosophy, namely: the body and the mind are connected in ways we do not fully understand

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