I know there are many different types of Withdrawal Syndromes, but I was wondering if it is possible to have Withdrawal Syndrome from a PERSON?
For Example- Spending a lot of time with a person, then not seeing them at all. Can this make you "sick" physically and mentally? If so, what are the symptoms?

Sure it can make you sick. The attachment to a certain person and then not having that person can effect your health. It all depends on the individual and life that your experiancing. Meaning if that is your only focus is that one person and then you lose that person then yes, it could have devastating effects. For example, this is of course people who are of later aged. A man dies of old age and his partner left behind is heartbroken and not to long after they pass away as well. That story I have heard several times. It all depends on your outlook on life. So why the question? Are you missing somebody? What symptoms have you been experiancing. Sick to your stomach, anxiety, etc..?

Joe

Not so much sick to my stomach-but more like loss of sleep, headaches, and anxiety.

Get out in the fresh air and meet new people and do the things you've always wanted to do .Work on yourself. The worst thing you can do is isolate yourself and just think about what was. Exercise and a good diet will help with the sleep and a lot of fun with fun-loving people will ease your soul and fill your time till the mind can get over the loss. It takes time.

You have not said who this person is and what relationship you had with them. Did they leave or die? Sadness and lonliness can certainly cause loss of appetite. Do you experience that? If you are not eating right that can cause headaches. Worry can cause anxiety. Explain a little more.

Yes, it is common and seen all the time in abusive relationships ( not sayingyours is, just where it is very easy to see) one side of the relastionship is and becomes dependent on the other. They were made to feel they deserve what they get and they are told over and over, that they can't make it without the other person. So if and when they try to leave, they emotionally can't, or can't stay gone, since they have become dependent on them for any and all emotional concern.

And it works the same on a long term relationship, you will see someone whose spouse dies, very often the other person almost gives up on living,

But of course with any dependency, you can break it by merely taking one day at a time, and doing what you need to do to get over this person,
Become involved in activities, don't set around and just think about them.
Change habits, eating places, basically start a new life.

You have good posts here to consider and I would only add this: if a person is TOO involved with another person and then suddenly isn't, it certainly does take a big toll on the person physically, mentally, emotionally and spiritually. The reasons for being too involved can vary from mental illness, addiction or abuse (like Fr Chuck mentioned) to more ordinary life experinece stuff like caring for a criticall ill person who then dies.

People who addicted to other people are codependant and if you would like to know more about that I would suggest the book, "Codependant No More" by Melody Beattie. In a nutshell it suggests codependants are somehow incomplete people who seek to be completed through over-involvement with others, which is not a healthy thing to do. Simply put, they are frequently people who were raised in dysfunctional homes where the child was forced to tolerate their healthy boundaries being trampled in some manner.

Healthy people have an entirely different experience when they lose a relationship. Although they are affected a bit differently in differing circumstances, the stages are fairly predictable and the person moves through them at a reasonable pace. There is no sense of being "stuck" for them.

Without knowing more detail, its difficult to tell what you are experiencing. I hope that gives you some useful perspective. If you have any questions, please feel free to ask them here. Thanks for posting.

Thank you all for your responses and advice, they are greatly appreciated.
And, since many of you think I need to go into more detail about my situation, I will: I was on vacation for a little over a week, and the first or second day of my vacation I met someone. We continued to hang out/spend time together everyday while I was on vacation.. but as we all know vacations don't last forever and I was forced to say goodbye too soon. We still keep in touch, but it's hard because we both took a great liking to one another. So another thought I took into consideration- is this similar to Separation Anxiety?

No, this is not the same as separation anxiety. And it ought not be occurring with something as casual as meeting someone while on a vacation. It sounds more like an adolescent crush now. Did you make any arrangement for staying in touch? How old are you?

Excellent responses overall.
In short, as others have stated, this is quite normal in many circumstances. It sounds like you really hit it off with this person in the short time you knew them. Perhaps even became a bit infatuated with them. When such a thing happens, the brain releases increased levels of many neurotransmitters, among these: oxytocin, norepinephrine and dopamine. These chemicals affect not only thought, but many cardiovascular functions, as well as other systems of the body. It's your body's way of encouraging bonding, in a sense. The shock of having this person taken away "too soon", could theoretically cause the levels of these transmitters to drop off more rapidly than your body could adjust to. Many off these chemicals help to regulate other nerotransmitters as well, such as serotonin. Lack of serotonin is most often implicated in depression, and certain other mood disorders, but does as well directly regulate production of melatonin, the "sleep hormone." Decreased melatonin production would, quite simply, cause a relative inability to fall and stay asleep. Your anxiety and headaches could quite easily be related to certain of these functions as well. Eventually, after the "honeymoon period", so to speak, these chemicals naturally wane anyhow, and that is when true love inevitably must take the place of infatuation in a relationship, or often it then necessarily fails. Simply put, gratification by something perceived as something more of an object, is replaced by the desire to now grant gratification to a subject now seen as largely independent of one's own self and desires. Inevitably, they often start quite mixed.
What Jesushelper76 said, is very true of life-long relations. The actual documented statistics are, that there is a 16 times greater chance than normal that the spouse of a recently deceased loved one will die within the first 24 hours. Inevitably the long-term outlook often isn't much more favorable. People often do die of a broken heart, but even loss in the short term can place enormous stress upon some people.
Codependence is a very valid theory, of which the psychological origins in childhood can be understood to some degree by studying the work of British psychoanalyst D.W. Winnicott. But often, what you describe is just a normal part of falling in love. Some people just have the capacity to rebound more quickly than others.