In this short presentation Dr. David Perlmutter explains how sleep quality directly influences the brain regions that govern decision‑making and appetite, leading to poorer food choices and a cycle of weight gain and further sleep disruption. He cites a study of 32 healthy young men who, after a night of total sleep deprivation, showed heightened amygdala activity (the brain’s impulsivity and reward center) and higher ghrelin levels, and were far more likely to choose an unhealthy snack over a non‑food item compared to when they had a full night’s sleep. Perlmutter describes this as a “disconnection syndrome” where lack of restorative sleep disconnects the prefrontal cortex (the rational, future‑oriented decision‑making area) and leaves the amygdala in control, making decisions more impulsive. The increased hunger hormone ghrelin further drives cravings for calorie‑dense foods. He outlines a feed‑forward loop: poor sleep → impulsive, high‑calorie food choices → weight gain → poorer sleep quality. The talk concludes with a practical message: prioritizing restorative sleep is a key leverage point for healthier choices, alongside diet, exercise, relationships, and time in nature, and is discussed in his new book “Brain Wash.”
Chapters
Hi everybody, Dr. Perlmutter here. Dr. David Perlmutter, obviously. You're going to be hearing much more from Dr. Austin Perlmutter soon. And having said that, our new book is called Brain Wash, and Brain Wash focuses to some degree on the importance of the choices that we make, not necessarily their importance, but what influences our decision-making. Are we impulsive, making wrong decisions? Or do we connect to the part of the brain that allows our decision-making to be more forward-thinking, more thoughtful, more in touch with, for example, future consequences of those decisions? One of the areas we talk about has to do with the importance of sleep in allowing us to connect to that part of the brain, the prefrontal cortex, that then allows us to make good decisions. And how, when we don't sleep well, when we are sleep-deprived, Or our sleep is not restorative, our decisions are more impulsive. And as it relates to food, we may not necessarily make great food choices. So, let's look at some science. Called sleep deprivation selectively upregulates or increases activity of the amygdala that's involved in food reward. This is an interesting study in which they took They really wanted to ask and try to answer the question, how does being deprived of sleep influence our choices? And in this case, whether we choose things like to buy things versus to eat things, as it were. They took 32 male, healthy male subjects aged 19 to 33 years, and they either got to sleep all night long or they kept them up all night. And they then confronted these participants with a simple choice. What would you buy at a given price? The same price, um, you're going to buy a snack food or you're going to buy a non-food item. In this case, it is a hat. At the same time, they're going to look at the amygdala, the impulsivity center of the brain, which is the subject of the study. And you see it here in the green arrow. That's, uh, in this what's called a coronal view of the MRI scan. Living in the temporal lobe, and they found some things that were actually really interesting. First, when looking at whether or not they bought at the given price the non-food item, which was a hat or whatever it was, people who had a normal night's sleep were more likely to buy the non-food item in comparison to the people who were sleep deprived, who instead were really strongly pulled to— Buy the food. At the same price, buying the snack food, the unhealthy snack food, a powerful indication that there's at least a relationship then between food choices and not getting a good night's sleep. At the same time, as I mentioned, they looked at the amygdala and they found that the— those who were sleep deprived had a demonstrable increased activity of the brain's impulsivity center. The amygdala, as opposed to the parts of the brain that allow you to make better decisions. We call that one area the prefrontal cortex. We call being disconnected from that prefrontal cortex disconnection syndrome, where we lock into the amygdala. And as we see here, not getting a good night's sleep disconnects us from the prefrontal cortex and causes us to use the amygdala to make our decisions and— Actions. Therefore, they are more impulsive. Another thing that was studied, which I think is really interesting, is the level of ghrelin. Ghrelin is a hormone that is involved in making us hungry. Higher levels of ghrelin are associated with increased hunger, and as you see here, increased ghrelin levels in those individuals who were sleep deprived. So they're hungrier when they— in the morning. Mm-hmm. And not only that, but the quality of choices that they make referencing their foods may not necessarily be appropriate compared with a night of getting sleep. A full night of sleep debt selectively increases the way people value snack food rewards compared with the non-food rewards, whatever they use, whether it was a hat or who knows. This result paralleled the increased activity of the amygdala. So again, Not getting a restorative night's sleep makes you choose the crappy food, more of it probably because your ghrelin levels are higher, and it is associated with increased activity of the amygdala and tends to disconnect you from what we're trying to connect to, the prefrontal cortex. And it sets up a— what we call a feed-forward cycle whereby having a poor night's sleep leads to poor food choices, which would then lead to being overweight and/or obese, or obese, which then leads to poor sleep. You know, the more weight you carry around, the poorer is your quality of sleep, and this creates a feed-forward cycle. So what did we learn? Once again, we learned that not getting enough sleep threatens our ability to connect to the prefrontal cortex, Locks us in more to the amygdala part of the brain. That's the part of the brain that is involved with things like making impulsive decisions. And in addition, how not getting enough restorative sleep can actually increase our appetites because, as these researchers demonstrated, not enough good sleep is associated with increased amounts of ghrelin, which is basically the hunger hormone. So the message is, in terms of reconnecting, making good choices, pay real good attention to the amount of restorative sleep that you get. We talk about that quite extensively in the new book, Brain Wash, and it's just, you know, one of the leverage points along with diet, along with exercise, building relationships, and even spending time in nature. Thanks for joining me. I'm Dr. David Perlmutter. Bye for now. Bye.
