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Antianxiety drugs (anxiolytics) fall broadly into two groups, the older, fast-acting drugs and the newer, slower-acting drugs:
• The fast-acting benzodiazepine drugs, such as Valium, Ativan, or Xanax, are potentially addictive and can cause rebound anxiety when they're stopped. The mood change following use of these antianxiety drugs is pronounced and rapid, similar to the effect of alcohol. It's unwise to drive or operate heavy machinery when using drugs in the benzodiazepine family. At certain doses these drugs can suppress the respiratory system.
• The newer antianxiety drugs, such as BuSpar (buspirone), cross the boundary between antianxiety and antidepressive drugs, are not addictive, and can be stopped abruptly with no ill effect. They take two to three weeks to work. The mood change following use of these drugs is more subtle and gradual, and sleepiness, if present, is less pronounced than with the benzodiazepines.
Please note that the antianxiety drug Ativan, a benzodiazepine, is often used just prior to chemotherapy to control nausea. In this limited usage it is unlikely to be addictive and can be an asset in anxiety and nausea control.

Antidepressant medication
The availability of todays more effective, safer antidepressants is a blessing for those coping with cancer. Unlike the antidepressants of a few years ago, which caused sleepiness, weight gain, or other undesirable side effects, to day's antidepressant medications are far safer and less disruptive of weight and sleep patterns. Antidepressants are also good pain relievers, although their mechanism as such is not entirely clear.

Some of the newer antidepressants can cause restlessness and insomnia for the first two or three weeks they are used. You might discuss with your doctor the temporary use of a sleeping pill until your body has adjusted to the antidepressant.
Improvement in mood is gradual with most of the antidepressants used today, changing slowly over a few weeks or months. The fullest effect is gained if the drugs are used continuously for months. Always check with your doctor before stopping an antidepressant, lest gains in improved mood be lost.

The best source for antidepressant medication is a psychiatrist. This specialist is the one most likely to be familiar with all antidepressants and their side effects and can rotate you through several until the best one for you is apparent.

Sleep medications
Sleep medications range from the very mildest, including over-the-counter antihistamines and Tylenol, to the stronger medications necessary for those using prednisone or those coping with moderate to severe anxiety Drugs prescribed for severe pain, such as codeine and morphine, also induce sleep.
The antianxiety drugs in the benzodiazepine family, such as Ativan, are also used as sleep aids. See "Antianxiety medication" for information about these drugs.

Some of the newest sleeping pills target those who have trouble falling asleep. They're cleared very rapidly from the body, so they are less useful for those having trouble staying asleep. For at least some people, these drugs might be addictive.
Some people use melatonin, a substance marketed as a food supplement, to aid sleep. Always consult your oncologist before using any drug, whether prescription, nonprescription, or a "natural remedy" marketed as a food supplement.

Summary
The effects of stress and personality on the inception and growth of cancer are unclear and are still being studied. Animal models indicate that a wide range of tumor responses to physical and emotional stress are possible, depending in some instances on the species, gender, stressor, season, previous exposure to stress, and biological state.
Regardless of the effect of stress on cancer, there are good reasons to reduce stress. Your sense of well being will improve, and you can lessen or prevent the chance of secondary illnesses.

Mental illnesses are among the most common conditions affecting health today. I am myself facing a lot of mental stress these days. Always having headache and feel like crying. Is this is a type of disorder i am facing and unable to understand.