Even very small children can experience sadness, although the way they express the feeling may not be the same as an adult.

There is a difference between feeling sad and being depressed.  Sadness tends to be felt over a short period of time and is clearly related to an event.  Its effects on functioning tend to be milder. 

Feelings of grief – sadness that is experienced after a loss of a loved one, loss of a pet, or even loss of status – are perfectly normal and should be expected after such an event. 

Worry and fearfulness are also common and quite normal.  Being afraid in threatening situations is a good thing: it heightens awareness, and gives you the motivation and energy to get out of harm’s way – the so-called ‘fight or flight’ response.

It is only when these feelings become chronic or start to interfere with a person’s enjoyment of life that they are considered to be abnormal and may signal the development of the more serious condition, depression, requiring intervention by mental health professionals.