well, mental peace depends on a lot of factors.
Like- If you had a fight or conflicts with someone you will be disturbed and as a result, you won't be able to sound sleep. Or if there is a conflict in the office with office colleagues, then you will be disturbed.
For all these reasons it is important to avoid such conflicts as much as possible.
here are some Vastu tips for this:
1. The sleeping position should be as per Vastu. Sleep keeping your head in the South direction for sound sleep.
2. Keep your Aura shining and strong. take a bath with rock salt once a week.
You can read full info on how to improve you aura at Vastu Compass Community.