In a blog yesterday, the bureau's educational psychology service senior specialist Michelle Chan Wai-man wrote that schools are busy with exams in January and February, when students face greater stress.

If their exam results are unsatisfactory, they may not be able to process their feelings and suffer from tremendous worries and disappointments.

"Teachers should help pupils understand that stress and unfavorable outcomes are inevitable. What's more important is to learn their own way to relieve stress and not allow negative emotions to accumulate in oneself," she wrote.

Chan cited research that drew attention to adequate sleep as it is key for learning, memory and maintaining a steady mood, while exercising and leisure activities can also help students sustain a positive mood and relieve stress.

"During exam periods, students should have enough sleep and keep a habit of healthy activities to take care of their own mental health," she said.

Chan said many students suffering from mental illness experience their first symptoms during adolescence, and early detection can lead to an early diagnosis.

However, due to low awareness levels, some students were not treated promptly - studies found some students had their treatment delayed for months or even years. In the meantime, they may suffer from skin and digestive discomfort as well as sleeping problems. In the worst case scenario, they may harm themselves or commit suicide.

Chan also said teachers should build friendly relationships with pupils so they will be more willing to seek help when they encounter emotional difficulties.

"We can only notice their special needs in mental health if we understand the students' personality," she wrote.

"Teachers can show pupils they care about them and begin conversations and activities with them to build stronger bonding."

"They should also remind students that they need not feel ashamed to tell others about mental health issues, such as insomnia, concentration difficulties, lower learning efficiency and mood swings. Instead of hiding them, they should be trying to let them heal on their own," she wrote.

She told teachers to keep an open mind when pupils seek help. "We should listen patiently, make no judgement, promptly express our care and acceptance and help students figure out how their teachers , family and friends can help them," she said, adding that they should refer the pupils to professional assistance if necessary.

Chan said teachers and parents are "gatekeepers" in protecting students, calling on them to read the bureau's guidelines about identifying pupils who possibly suffer from depression, anxiety, selective mutism and Tourette syndrome.

The bureau has also hosted seminars on preventing student suicides. Two of these seminars were held last month and were attended by 1,750 principals, teachers and social workers from secondary and primary schools.