Can I use it every day or night?

Yes. There is no harm in taking Zenbev everyday or night, however, it may not be necessary as there is a positive effect felt for a few days after you stop using it. The best rule of thumb is that it takes a few doses before its optimal benefit is seen and it continues to work for a few days/nights after it was last taken. One way of optimizing this benefit is to take the mix for 5 days/nights and then stop it for 2 days/nights. Once your sleep problem is under control it is easy to stop and may not be necessary to remain taking indefinitely.