Here's how I experience and understand this subject:

In an ideal situation all the chakras are open and awake 24/7. It's the natural immortal state of being. The more active your chakras are more alive, energetic and awake you are. This is why I understand that some say that they should be partially closed at times. If you want to be unnoticed in a crowded place, it's better to hide some of your light. If your chakras are very open/awake you radiate a lot of light. Others will notice this and become attracted to you.  About sleeping: If your energy level is very high it's naturally difficult to sleep. Some people seems to be saying that sleep is not necessary when you are enlightened enough. But as far as you're not as enlightened your body really needs some rest and it's obviously wise thing to slow your energy down a bit when you're starting to sleep. At the same time it should be noted that as your energy levels rises you need less sleep.

How to keep chakras partially closed? You energize your chakras with your mind by placing thought into them. Less you place your thought into a chakra less energized it becomes. Chi-kung practitioners say that chi goes where the mind goes.

About the 3rd eye: I would advice to keep the 4th (pituitary) eye with the heart (thymus) center activated all the time instead, it will naturally activate the 3rd eye as a side effect.

It should be understood that your state of being affects those around you and this is why you should actually radiate love and life as a free gift to all, all the time. In case you care about happiness, health and well-being of other living things. Keeping the pituitary and thymus activated you will radiate love, light and life. It's the old "if your eye is healthy your body is full of light" thing that Jesus spoke about.