Low self-esteem makes us feel bad about ourselves. But did you know that over time it also can cause the development of serious mental conditions such as depression?

自卑让人自我感觉极差。你知道吗，长期自卑会导致抑郁等严重的精神问题。

Self-esteem is, very simply, the set of feelings you have about yourself. It's developed by your experiences, thoughts, feelings, and relationships.

Unlike self-knowledge, which refers to how much you know about yourself, the core of self-esteem is formed around whether you like yourself or not. 

Depression is much more than just feeling sad. It saps your energy, makes everyday activities difficult and interferes with your eating and sleeping patterns. Psychotherapy and/or medication are highly effective in treating depression. 

There are several types of depressive disorders, including major depression, persistent depressive disorder, psychotic depression, postpartum depression, and seasonal affective disorder (SAD). 

Clinicians use low self-esteem as one possible symptom when they diagnose the psychiatric condition of major depressive disorder. They don't necessarily care whether low self-esteem causes the depression or vice versa.

However, personality researchers have long wondered about the chicken-and-egg problem of self-esteem and depression. Certainly, if you dislike yourself, you'll be more likely to be depressed. Conversely, if you're depressed, you'll be more likely to feel bad about who you are as a person.

The only way to disentangle the highly related concepts of self-esteem and depression is through longitudinal research, in which people are followed up over time. A study on depression, conducted by University of Basel researchers Julia Sowislo and Ulrich Orth, contrasted the competing directions of self-esteem to depression vs depression to self-esteem.

The findings almost all overwhelmingly support the vulnerability model of self-esteem and depression. Over time, low self-esteem is a risk factor for depression, regardless of who is tested and how. The study indicated that low self-esteem causes depression but not vice versa.

Therefore, if a person has low self-esteem, there's an increased risk of developing depression. This is a very important discovery because it shows that improving a person's self-esteem can make him or her feel better.