Being absent and missing out on class can be hard on children as they get to miss out on valuable lectures. This can often times lead to poorer performances, and worse, can lead to ridicule from peers. But the reason behind children's absenteeism may be far more problematic than missing out on class as new research finds it may be linked to their mental health.

Students who are frequently absent from school are more likely to have symptoms of psychiatric disorders, according to Jeffery Wood, associaten professor of educational psychology and psychiatry at University of California, Los Angeles, who led the study.

In the study, researchers looked at more than 17,000 children in 1st through 12th grades and found that between grades 2 and 8, students who already had mental health symptoms missed more school days over the course of a year than they had in the previous year and than students with few or no mental health symptoms.

These frequent absents, researchers said, is linked with a higher prevalence of mental health problems later on when they reach adolescence.

Findings al show that middle and high school students who were chronically absent in an earlier year of the study tended to have more depression and antisocial problems in subsequent years, leading to missing additional school days in the following years.

Wood noted that their findings may aid others in helping students address mental health issues that in turn, prevent the emergence of chronic absenteeism.

And indeed, mental illness among children must be addressed soon. This is because the problem has become so common that about 20% of American children suffer from a diagnosable mental illness, and that around 5 million American children and adolescents suffer from a serious mental illness, according to MedicineNet.com.

The most common among the mental illnesses in children are anxiety disorders, disruptive behavior disorders, eating disorders, learning and communication disorders, and even schizophrenia.

But in order to successfully deal with a mental illness, a person must be able to identify when a child is suffering from them. Though symptoms may vary from one mental illness to another, some symptoms that generally appear when a child has a mental disorder are:

- Inability to cope with daily problems and activities

- Changes in sleeping and eating habits

- Defying authority, skipping school, stealing, or damaging property

- Frequent outbursts of anger

- Long-lasting negative moods

- Changes in school performance, such as getting poor grades

- Loss of interest in friends and activities they usually enjoy