I wear my pink

I wear my pink pajamas in the summer when it's hot;

I wear my flannel nightie in the winter when it's not.

But sometimes in the springtime and sometimes in the fall,

I jump between the covers with nothing on at all!

I learned that silly song at a Girl Scout summer camp but it's been running through my head recently. With all the earthquakes, or potential earthquakes, here, it's probably unwise to "jump between the covers with nothing on at all."

I wonder what people normally wear to bed in Tokyo.