the right is Bed, and the left is a person, a person is sleeping on a bed.
As I mentioned in other posts, the original characters were written in bamboo slips, which were very narrow, so people wrote or drew characters in vertical. This character is a vertical drawing of sleeping.
Let's turn it 90 degree
Dream occurs in sleeping.
Its big seal script is
under the eye, something like 八 is the body of the person.
The bottom part
Its small seal script is
Its clerical script is
which is similar to the clerical script.
The song typeface for simplified character is
The bottom is same to the traditional character, but the top one become 林，which means Forest, nothing to do with Dream. The reason why the Eyebrow is changed to Forest may be because people might have misunderstood the top is a grass head (草字头), not the eyebrow.
Its Pinyin is Meng4.