What can I take with vortioxetine to help me sleep?

I agree with with massos's suggestion unless your pharmacist can suggest a good OTC.
I was prescribed a low starting dose of Seroquel (quetiapine) for Bipolar ll depression which is working well but as an added bonus it's cured my insomnia. 50mg is the recommended initial dose and that works very well for most people.
The only thing I'd add is that you may experience a mild "hangover" the next morning for a few days until your metabolism adjusts to the medication.
Best regards and I hope you're getting your Zzzz's very soon.
Wildcat

There is an atypical antipsychotic called Seroquel (quetiapine), it is used off label to treat sleeping disorders at a low dose of 50mgs..
It is quite effective and it does not interact with your antidepressant, you should ask your Dr. about it. I know everyone is different but as I mentioned many people use it for insomnia/sleeping disorders.

Interaction report: https://www.drugs.com/interactions-check.php?drug_list=3490-0,1979-1274