Have there been nights when the clock says two in the morning and a sentence a colleague said at three that afternoon is still going round and round in your head? When the mind analyzes every meaning that might be hidden in it, while knowing perfectly well that thinking about it changes nothing — and still cannot stop?

Or times when a small mistake pulls you back into "I have always been like this," and then, worse, has you digging up old failures to pile on top of it?

If any of this is familiar, it is not simply overthinking in the ordinary sense. It has a name in the research literature — rumination — and it is one of the mechanisms most strongly associated with depression.

Many people conclude that they simply do not know how to let go. In reality the difficulty may have nothing to do with intention. It may lie in a loop of rumination that returns the brain to the same thought again and again.

What rumination is, and how it differs from ordinary thinking

Rumination is a repetitive, passive dwelling on negative thoughts or feelings that does not lead to a solution. Research defines it as thinking that is self-focused, oriented toward the past, and negative in tone — arising automatically and circling within a narrow range of concerns, over and over.

What separates rumination from ordinary problem-solving is that it does not lead anywhere. Someone analyzing a problem eventually arrives at a conclusion or a plan. Someone ruminating circles in place, thinking the same thing repeatedly and going nowhere at all.

What is interesting is that many people who ruminate believe, without recognizing it, that "if I keep thinking about this, one day I will solve it." Researchers call this a metacognitive belief — a belief about one's own thinking. The irony is that this belief does not reduce rumination but intensifies it, because it gives the brain a reason to treat the circling as useful, when in fact it leads nowhere.

What a ruminating brain is doing

Neuroscience research has found a clear association between rumination and a brain network called the Default Mode Network (DMN). This network becomes active when we are at rest and turning over matters concerning ourselves — the past, the future, and our relationships with others.

In people with depression, research has found that connectivity between the Default Mode Network and the subgenual prefrontal cortex — an area involved in emotion and in socially withdrawn behavior — is stronger than in others, and the strength of that connectivity is associated with the severity of rumination. Put simply, the brain has built an unusually tight network binding thoughts about the self to negative emotion.

Another study worth noting had participants listen to criticism and to praise directed at them while their brains were scanned. The researchers found that the group at risk of depression showed clearly heightened Default Mode Network activity on hearing criticism, but not on hearing praise — and that this heightened activity was associated with each individual's level of rumination. Which suggests that these brains may be particularly sensitive to taking negative information and turning it over in relation to the self, more so than positive information, even before depression has developed.

Self-blame: when a small mistake becomes evidence

Self-blame is a form of rumination found very commonly in depression. Unlike taking appropriate responsibility for a mistake, self-blame tends to magnify a small error into evidence confirming a much larger negative belief about the self.

A minor slip at work, and the brain does not simply register that this piece of work went wrong. It becomes "I am useless." Someone forgets an appointment with a friend, and the brain does not read it as forgetting on this one occasion. It becomes "I have always been a bad friend." This pattern of thinking then reaches back for similar old memories and lines them up as evidence, so that the negative belief about the self grows stronger each time a new event triggers it.

Overthinking: the trap where trying to finish the thought never finishes it

Overthinking, in the sense connected to rumination, tends to arise during periods of high stress. Research has found that major life changes — losing a job, the end of a relationship, academic or financial pressure — all make overthinking more likely, and that accumulated overthinking in turn raises the risk of both anxiety and depression.

The mechanism behind it involves an imbalance between two brain networks. The part involved in dwelling on the self works too hard, while the part that should regulate and switch off those thoughts does not work well enough — like a switch that ought to turn off normally but is stuck in the on position.

So how does anyone leave this loop?

Because rumination is an automatic pattern of brain activity connected to a network that is working beyond what is needed, trying to stop it by telling yourself to stop thinking usually does not work. That is a conversation with the conscious mind, while the loop running is an automatic mechanism deeper than that. It is also why telling yourself to let go usually does not work: someone ruminating is not choosing to think. The brain is running an old circuit automatically.

Working with patterns of thought at the level of the subconscious, through a directed process, may open space for the brain to learn a different way of responding to negative thought. Not suppressing or ignoring those thoughts, but easing the intensity of a connection between thoughts about the self and negative emotion that had become unusually tight.

At NBRH we understand that rumination is nobody's intention. Nobody wants to lie awake at two in the morning analyzing the same sentence until sleep is gone. Nobody wants to magnify a small mistake into proof that they are inadequate. And nobody wants to be a person who cannot let go while knowing perfectly well that the circling helps nothing. It is a pattern the brain has learned and bound too tightly.

And a pattern that was learned can be learned differently.

To understand how other factors — childhood, personality, and stress — connect to depression, we have written “Is Depression Really Caused by Brain Chemistry?”, which also sets out what hypnotherapy can help with and where its limits lie.

Why Some People Cannot Let Go: Rumination and Depression