DAYSTAR by Rita Dove.

She wanted a little room for thinking:
but she saw diapers steaming on the line,
a doll slumped behind the door.
So she lugged a chair behind the garage
to sit out the children’s naps.
Sometimes there were things to watch-
the pinched armor of a vanished cricket,
a floating maple leaf. Other days
she starred until she was assured
when she closed her eyes
she’d see only her own vivid blood.
She had a hour at best before Liza appeared
pouting from the top of the stairs.
And just what was mother doing
out back with the field mice? Why,
building a palace. Later
that night when Thomas rolled over and
lurched into her, she would open her eyes
and think of the place that was hers
for an hour-where
she was nothing,
pure nothing, in the middle of the day….

Reference:
Rita Dove