Sparky,
This is what I found regarding your question...
Ativan is sold in three different dosages: .5 mg, 1 mg and 2 mg, and each patient’s dosage is different depending on doctor, severity of symptoms and situation. Because of this, there is no one way to gauge how long the effects of the drug will last on a person. Although common reports claim that effects of the drug will last from six to 12 hours, a person who is taking multiple doses daily for a number of years may not feel the effects for as long as someone who has just begun the medicine. Age is also a factor in its effectiveness, as it has been found that in older people the effects may last longer
Read more:
http://www.ehow.com/how-does_5202168_long-do-effects-ativan-last_.html#ixzz30QyijRIFI hope that this helps, that you get a good night's sleep, and that you have a great day tomorrow!
S.C.