I hear people say all the time they wake up in 
the middle of the night and can’t fall back to sleep. When I ask them why, they tell me they have so much running through their heads and they just can’t relax their brain. I am sure this happens to your clients all the time and it happens to me too. Something that helps is to keep a notepad next to the bed and when you wake up you can write down what’s in you head. You might think this will activate your brain, but instead is allows you let go of the task knowing it’s there for you in the morning. You write it down to remember and allow your brain to forget.
Perhaps the next time a client tells you they didn’t sleep well because of so much swimming in their head; have them give this a try and get a good night’s sleep.