What they talk about in this book is the fact that meditation has two separate lines of effects. One of those lines of effects are things that change your state. So you're stressed. You sit down, you meditate and you relax and you go into a particular state. The other are the changes that occur over time and those are changes in trait. So personality can actually change with long bouts of TM meditation or repeated meditation. In any case, the reason we're talking about "Altered Traits" today is because certain types of meditation can get people's brains into states that very closely mimic slow-wave sleep.