Book Review: Switch on Your Brain: The Key to Peak Happiness, Thinking and Health

Leslie Seidner

This is a guest post from Leslie Seidner, a writer who researches and writes about positive psychology, anxiety, and brain health. She also happens to be my sister and favorite person to talk about books with!

I have been stressing about the effect that stress is having on my brain, which I realize is wholly unproductive and ridiculous. But I am really struggling with caring for my aging parents while simultaneously worrying about being next in line for cognitive decline. I am working hard at being a good mom to my fifteen year-old daughter, even though I am really tired of my mom job; I am trying to nurture my 27-year marriage and parent my three adult children who live scattered from the West Coast to the East Coast and have different issues and needs. It’s quite overwhelming, and most of the time I feel as if everything I am doing is futile and an abysmal failure and no one is getting what they need, especially me. This is not the way that I felt five years ago, but it is how I feel now. I don’t like it, and I know it’s not good for me.

Up until this week, I could not explain how I knew that all this stress was bad for me, but I am a very proactive person, so, I decided it was time to do something about the stress and about my attitude.  I cannot get rid of any of these people, and honestly I love them all too much to do that, so I decided to put some effort into figuring this out, instead of just running around blindly spinning my wheels and feeling lousy.  

The first helpful thing that I found was Caroline Leaf’s book Switch on Your Brain: The Key to Peak Happiness, Thinking and Health. I read it, and I read it again and took notes.  It definitely explains why stress is bad, and I think it has some really important information for all of us to think about. I am therefore going to summarize it for you all (that way even non-readers can reap some benefits from it!)

Dr. Leaf proposes that our minds are very powerful and actually control our brains. This is fantastic news for those of us with less than desirable heredity in the brain deterioration department, because if our brains controlled our minds, we’d have no chance to have any impact on the process. More on that later.

She emphasizes that we have been given free will, therefore we can make choices about our thoughts, and choose to build up healthy thoughts and tear down toxic ones. In doing so, we will actually change and grow the structures in our brains. Dr. Leaf’s book alerts us to be careful about what goes into our brains and about what comes back to the surface from within, because both healthy thoughts and toxic thoughts can be built up with mental rehearsal. And both will change the actual structures inside our brains. This is the concept of neuroplasticity.

Here is a summary of Dr. Leaf’s explanation of how this process works:  the hypothalamus and thalamus take in sensory information from our five senses; the hypothalamus tells the other brain parts to release chemicals in response to the sensory input or thought (like serotonin and glutamate), while the thalamus sends the thought, from the sensory input, over to the amygdala. The amygdala attaches emotion to the thought and sends the whole package (“nugget”) over to the hippocampus for memory storage and to the frontal lobe for balancing of the emotions, reasoning, analyzing and deciding.

Here’s where the rubber meets the road:  the hippocampus has tons of stress receptors that are designed to reinforce memory, but they get clogged up with stress, if that’s the emotion that has been attached to the thought. The thought/emotion nugget gets circulated around through the hippocampus and frontal lobe (through the basal ganglia as well, where thoughts and emotions are turned into actions) for 24-48 hours; the nugget gets amplified upon each pass through the hippocampus. Once that nugget has been amplified, it is conscious and therefore changeable; our heart acts like a checking station, confirming or denying the decisions being made. At this point, we decide whether to keep the thought, build protein trees (actual structures in the brain) to keep it, or tear it down.  

I was very excited and also very scared when I read this. Excited to think that maybe I have some control over the growing or shrinking of my brain and scared to think of the damage that I have already done to my brain with toxic thinking and stress up to this point.  Stress literally shrinks the hippocampus, and makes memory storage difficult (as in Alzheimers and other dementias).  However, according to Dr. Leaf, I can grow my own brain back thanks to the brain’s amazing neuroplasticity.

My favorite thing about Leaf’s book is she ties every one of her recommendations to biblical passages and principles and encourages us to look to the Bible for answers. Let me explain.

Dr. Leaf first references Romans 12:2 (which just happens to be my very own life verse), “Do not conform to the pattern of this world but be transformed by the renewing of your mind. Then you will be able to test and approve what God’s will is—his good, pleasing and perfect will” (NIV). Instead of doing what everyone else does, namely stressing, worrying, spinning, and busily rushing to and fro without much purpose, if you renew your mind by meditating on the Word and praying, you will find God’s will for your life and live.  Sounds pretty appealing to me, and she elaborates.

Your thoughts become who you are…literally. Philippians 4:8 says, “…whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable-if anything is excellent or praiseworthy-think about such things” (NIV). So we are called to meditate on good stuff, not to obsess over bad stuff. Just writing that makes me feel so much more relaxed; does it do the same for you?

Finally, she says that we are wired for love, but we learn fear. The Bible says it this way in Second Timothy, “God has not given us a spirit of fear, but of power and of love and of a sound mind” (2 Timothy 1:7).  Well, here we go. I already know that fear is really a lack of faith, and that fear and faith occupy the same space inside our minds. If it’s full of faith, there’s no room for fear. I fear losing my mind, and I would really like to have a sound mind all the way until I die. When I am told that I am meant to have a sound mind, and not to fear, I am incredibly encouraged.

Leaf has a 5-step process to help us get rid of toxic thoughts and replace them with healthy ones. The steps are: gather, focused reflection, write, revisit and active reach. Now, I have done some reading and studying on “Mindfulness” and  Leaf’s recommendations are very similar to the concepts inherent in the Mindfulness movement. But what’s unique is Leaf ties each of her steps to specific brain areas and explains why each step is necessary and valuable.


When we “gather,” the amygdala provides input to the mind about the emotions connected to the thoughts (this is the Romans 12:2 thing).


When we “reflect” the thalamus and hypothalamus provide input on motivation and the memory networks provide input on the existing memories (this is Psalm 46:10, “Be still and know that I am God”).


When we “write,” the central hub in our brains mixes and integrates all of these things together and consolidates our thoughts.


And when we “revisit,” the heart acts as the checking station and helps us make a decision and design a new healthy thought to replace the toxic old one.

Active Reach

The fifth step, the “active reach,” is arguably the most important. It is where we practice using the new healthy thought until it is automatized like a habit.  This is where the words and actions line up the thought with its beliefs and feelings. This happens in the limbic system and makes us feel as if the new thought is true.  This is where mind/heart congruence occurs. By using the new thought at least 7 times a day for 21 days, we can ingrain it into our brains and replace the old toxic thought forever.

I am going to get started! 

I’ll let you know how it goes.

Comments are closed