In the Heian period (794 to 1185) — the peak of the Japanese imperial court and noted for its art, especially poetry and literature—the women of dynasty wore their hair very long because hair defined whether they were beautiful.
Having “longer, straighter, blacker, and shinier” hair was the beautiful women’s pride.
An essay written in the period, The Pillow Book (completed in the year 1002) says that hair without body was considered to be vulgar and cut off. Women probably competed with each other for the most beautiful hair.
They wore the hair longer than their heights; therefore, they spent a great deal of time and effort on taking care of their hairs.
Using rice water (water that has been used to wash rice), they started washing hair in the morning, and by the time their hair got dry, the sun went down.
When they go to sleep, they were so careful about their hair to not damage; they kept the hair in boxes or coil hair up by pillows.
Images are from Wikipedia
This is JAPAN Style!