COASTROAD Hearth & Patio I can't be precise, because this isn't my project, so the best I can offer is an educated guess.
That appears to be a Majestic direct vent fireplace, which is about 33" tall, with a mosiac tile surround about 6" high, plus a mantel header, crown and shelf about 9" high, so I'd guess the mantel is about 48" high.
Or I can look at the wall switches at the left and right, knowing that the electrician likely put them at 48" off the floor, and guess the same thing.
Even a simple chair in the corner by good natural and electric lighting, for reading any time (yes even those 4 a.m. bouts of insomnia) can encourage a broader usage of the bedroom.
Not for the look. Sample of how a more traditional mantle could sit in a corner. One side of corner is an entry so the depth of the mantle can't project to far into the open space.