You will certainly not experience all the reactions described here. The important thing is to remember that it is normal to undergo a reaction.
In the days and weeks after the incident your thoughts and imaginings can quite easily return to what happened. Sense impressions can appear and cause you to relive some of the severe impressions and strong feelings associated with the event.
This can be very frightening but is a completely normal reaction.
Re-living and intrusive thoughts can be unpleasant and they can arrive at any time, often when you are about to sleep.
Sleeping difficulties are very common.
You might find it hard to fall asleep, only sleep lightly and suffer from nightmares.
Many people find that it can be painful to wake in the morning and be confronted with the new reality and what has happened.
Many people experience a whirl of thoughts and that it is hard to complete one thought before the next one comes along.
Your memory may be impaired and the ability to concentrate noticeably reduced.
Which is why it can be hard to read even short texts or watch a movie.
The body reacts
Your body may show signs of stress and being overloaded. It is normal to experience stomach problems and nausea.
Many people feel chronic fatigue or tire quickly.
This can lead to work or domestic problems, and it may be temporarily difficult to live up to expectations.
Feelings of guilt
Some may experience feelings of guilt at being alive or in good health when there are others who have lost their lives or been injured.
Perhaps you blame yourself for not doing enough to prevent what happened. "If only I ..." is a very common thought.
Despair and irritability
In the period following a traumatic event many feel sad and despairing, and it can be hard to cope with existence and the future. Some people are more irritable with people around them, who might have difficulty accepting or understanding the change that has taken place.
This can lead to misunderstandings and create problems both in the family and at work.
Your reactions are very individual and of course dependent on what happened.
You might be overwhelmed with a feeling of being at risk, a person who could be struck by misfortune and tragedy at any moment.
The illusion that "bad" things do not happen to me has been shattered and you may feel vulnerable and insecure about when the next accident or tragedy will strike you.
This can result in an understandable but misguided tendency to be overcautious in relation to your own and other people's safety.
The meaning of life
Many people will go over what happened again and again in their minds looking for an answer to why it happened. It is normal to be preoccupied by what meaning life now has in light of what happened.
If for example, an accident has occurred, you might be concerned that the event should not have happened in vain, and that someone must be made to take responsibility.
This can give a sense of justice and form of comfort and a hope that in the future other people will be spared from suffering the same fate.
Some may find that their life no longer has any meaning and they grow indifferent to themselves, others or to things that formerly meant a lot to them.
Read more about children's reactions here.