Nayotake no yo nagaki ue ni hatsushimo no okiite mono o omou koro kana - Kokin Wakashu(English Translation & Meaning)

なよ竹のよ長き上に初霜の
おきゐて物を思ふころかな

Roma-ji: Nayotake no yo nagaki ue ni hatsushimo no okiite mono o omou koro kana
English Translation: Long as the sections
of the pliant bamboo, the nights,
and on top of that
like the first frost I lie awake
and brood in these days of mine.
Meaning: The nights are long, like the long sections of a pliant bamboo, and besides, I stay up like the first frost settling, lost in brooding these days.
Commentary: Book Eighteen Miscellaneous Poems II 993

Headnote: "Composed in the Kanpyō era, when I had been appointed an official of the embassy to China, on an occasion when the men were drinking sake in the guardroom of the Crown Prince's palace"
In the Kanpyō era of Emperor Uda, the author was appointed an official of the embassy to Tang China, and composed this when the men were drinking sake in the guardroom of the Crown Prince's palace. He says that he cannot sleep through the long nights and stays up brooding, hinting at his unease before the long journey to China.
This embassy was called off on the recommendation of Sugawara no Michizane, and the author never went to China.
The author, "Fujiwara no Tadafusa" as written in kana, is Fujiwara no Tadafusa. Versed in gagaku court music, he is said to have composed the piece Kochōraku. He is one of the Later Thirty-Six Poetic Immortals.

The first line, "the pliant bamboo," leads to yo in the second line, since the sections between bamboo joints are called yo.
The second line, "long ... the nights," contains the pivot word yo, the "section" of bamboo and "night."
The third line, "like the first frost," leads to oki in the fourth line.
The fourth line, "I lie awake," contains the pivot word oki, frost "settling" and a person "staying up."
The last line, "and brood in these days of mine," ends with the exclamatory kana.
Author: Fujiwara no Tadanobu
Source: Kokin Wakashu
Prev Poem: Akazarishi sode no naka ni ya irinikemu waga tamashii no naki kokochi suru
Next Poem: Kaze fukeba okitsu shiranami tatsutayama yowa ni ya kimi ga hitori koyuramu