MANILA, Philippines?Some people are just prone to negative thinking, seeing the negative side of things. That doesn't mean they're depressed; they just tend to see things on the dark side. Some people talk of mood swings, but a bipolar disorder's extreme highs and lows disrupt normal everyday functions.

A bad squabble or breakup with a loved one and feeling blue doesn't automatically qualify one to be clinically depressed. So what is depression?

Affecting 121 million people worldwide, the World Health Organization estimates that by 2020 depression will become the most prevalent illness. One out of five people will experience a major depression in their lifetime.

According to the Natasha Goulbourn Foundation, depressive disorder is an illness that involves the body, mood and thoughts-interfering with normal daily functions and affecting the mental, physical, emotional and spiritual well-being. Here are signs to look for in a depressed person:

Persistent sadness, anxiety or "empty" mood
Sleeping too much or too little
Waking up in the middle of the night unable to sleep again
Marked reduction of weight or weight-gain-eating too little or eating too much
Loss of pleasure and interest in activities once enjoyed, including sex
Restlessness, irritability
Persistent physical symptoms that do not respond to treatment (such as chronic pain or disorder)
Difficulty concentrating, remembering or making decisions
Fatigue and loss of energy-no energy to get out of bed
Feeling guilty, hopeless or worthless
Thoughts of suicide or death

"Depressed people feel ashamed and tend to avoid physical, social contact. They feel they don't deserve attention. The worse thing you can do is to try to talk a person out of depression because that would prove you don't know how bad the situation is," Dr. David Spiegel said.

If you checked on several signs, or if you know of someone who checked on several of the signs above, please consult a doctor or a professional counselor.

Anne A. Jambora