Hello, Numbness and increased heart beats can be symptoms of anxiety. Its important to know the root cause behind your insomnia. Treating just insomnia will not help rather root cause causing insomnia need to be treated. Psychiatric medicine usually take some time to act. Ambien is a sedating drug so it helped in sleep whereas Zoloft doesn't produce sleep but treat underlying depression or anxiety. You might need combination of drug in the initial state.

Its cause of anxiety but it needs to be further investigated are you undergoing stress of any kind personal or work related? I believe you should talk it out because even when medicine is on you can have these symptoms time to time and you should know through psychotherapy techniques how to manage them. consult with me or any psychologist for counseling & therapy. connect with me through practo app. all the best more power to you

The current features are more suggestive of anxiety disorder.need further info regarding the symptoms

Your symptoms as described by you suggest , you are having sleep problems along with anxiety issues. Depression needs to be ruled out. Zoloft( sertraline) takes one to two weeks to show improvement. After a week if no improvement, dose has to be increased. For few days till your sleep normalises, adding a benzodiazepine with sertraline would help. Changing the doctor and medications will not help. Have patience and stick to a doctor.