8 Hour Developers are a type of  Spray tan solution which goes on, dries and is worn for 8 hours before you have a shower to wash it off. 

You might like to leave it on longer because you want to sleep in it, and that's totally fine.  The most important thing is that you leave it on for the initial 8 hours to allow it to work. 
After that, the developer stops developing anyway, so you are safe to sleep in as long as you like, and wake up bronzed.  

Tuscan Tan Spraytan 8 Hour Developer

Choose light, medium or dark.
This tan is left on for 8 hours before you rinse. The most popular tan in Melbourne for brides, Tuscan Tan is made in Port Melbourne with clean formulations that keep your skin hydrated. Needs to be left on for minimum 8 hours before you shower, but is okay to be left on up to 24 hours if necessary.

allow 20 minutes $58

 “I recently found this gem after reading all of their great reviews. What a great find! Natashas is amazing - so helpful and really listens to what you want. The Tuscan tan is perfect every time. I can't recommend more highly, 5 stars.” 
— Ruby Heaslip, Google review