Synergy Purify is a blend of essential oils for aromadiffusion that creates a purified atmosphere. The general recommendation is to use it in a clean and well ventilated room. If you want to use it at night to sleep, the recommendation is to scent the room beforehand for about 20 minutes and then switch off. You can see the 'how to use' section above and the following question 'How to use Synergy Purify'.