Meditationis the method of choice for spiritual practice in many religions. The benefits of meditation don't stop at this level though. Your mind and body benefit immensely from meditation. There are few drawbacks though, one should be aware before taking up meditation.
The problem is ... within us. We all carry a baggage of traumas buried deep down in our subconscious minds. These are unpleasant events, consequence of our own or other people actions that affected us. Our minds try to protect us by covering up these experiences. In other words, we forget. Or do we?
These memories remain down there in our subconscious mind and affect us at an emotional level. They also affect our thinking process and our behavior.
We may forgot the facts or the details but similar circumstances will bring back the unpleasant emotions we once experienced. That is why sometimes we may feel depressed, angry, or unhappy without a reason. They may even affect us, with a Freudian twist, as a dream of an animal chasing us. All the same: this is the subconscious memory of uncomfortable emotions and feelings we once experienced.
We can also dissociate or disown these memories and this is another way our mind deals with them. So, you are going along and you meet somebody that acts in a way that reminds you of your own regrettable behavior that resulted in a trauma inflicted to yourself or somebody else. You will dislike that person without an objective reason because you disowned that behavior. Did it happen to you?
Meditation is all aboutawareness. In the process of becoming aware of our thoughts, a key ingredient in meditation, we may eventually bring back all sort of memories. Good memories may resurface bringing back happy feelings. Mind does not segregate the bad memories though, so we may remember things we strongly wanted to forget. And our mind did just that before meditation brought them back.
So you may say then: do not meditate! Well, this is a matter of preference. Some people prefer to live life on autopilot some others prefer to become aware at a more subtle level.
Also, sooner or later in our evolution as a human being we must deal with these uncomfortable memories anyway. The Eastern mystics call them karma. In science they are part of the subconscious mind.
Once you dealt with those traumas and let them go, you will be no longer susceptible to the specific unconscious memories and negative emotions.
You will be living a more balanced life, with less mood swings, with less ups and downs. This does not mean living a less exiting life, but rather a life where you are in control of your emotions and eventually choose the positive ones. You will be happy, or happier more often, to say the least.
There are some very efficient ways to deal with this meditation upheaval . The key is to let go and detach emotionally of these thoughts.