This is a simple technique that gives you a significant boost to your lucidity. It is also generally considered a requirement for WILD techniques during the night, as you want to be close to REM to do WILD.

To do WBTB, you wake up 4-5 hours after you've gone to sleep. Then, you spend a brief amount of time raising your awareness, preferably without making yourself more awake overall. Go to the bathroom, get a glass of water, or spend a few minutes meditating.

The duration you're awake depends on what you want to do and what works for you, it can be anything from a few seconds to half an hour.