Can ativan (lorazepam) actually CAUSE insomnia? I've been taking it for sleep and I've been getting less and less sleep.

Paradoxical. Paradoxical reactions may occur with any sleep medication, but is notorious with benzodiazepines, including ativan (lorazepam). Please inform your prescriber that you're having this difficulty such that you may discuss an alternative treatment for your insomnia.
Sedating meds. All hypnotics and benzodiazepines have the ability to produce tolerance, so the same dose has less effect over time--possibly leading to feeling more anxious. CBT for Insomnia can address both the behaviors and the thoughts (I'm not going to be able to fall asleep, etc)that feed into insomnia and make it worse. Please keep some sleep diaries to figure out what all factors might also relate to anxi.
Restlessness. It has and can lead to restlessness. Some even get fidgety. Would suggest to call ur doctor for adjustment of medication.
Insomnia, Ativan (lorazepam) I understand your concern about less sleep. Ativan (lorazepam) is not a specific medication for insomnia. It is for anxiety. Usually, the side effect is sedation. Side effect of insomnia is not common. Please go to Grand Canyon National Park in your State and feel Wonder and peace. Then see a psychiatrist about your journey of life, Ativan (lorazepam) benefits and side effects, Therapy and other medications if needed.
Not best zzz med. Ativan (lorazepam) is not the best sleep medication. While it is always possible that you have a bed response to it, a trial of a better sleep medication might be in order AFTER your doctor figures out why a 25 year old is having trouble sleeping.
Not usually. Lorazepam can help with sleep initially but tolerance to the med is common and the effectiveness decreases with chronic use. It usually does not cause insomnia. The dose may need to be adjusted or an alternative sleep med may be needed.