I have often wondered how Radharani can go to sleep, since she is missing Krishna so much. But last night I read why in a book, and here is the pastime. It starts with Radharani hurrying home after being with Krishna at night so as not to be caught.
Radha, surrounded by Her sakhis, entered Her house unseen and lay down in bed. Feeling intense suffering in separation from Krsna, Radha started crying. Radha, in a voice choked with yearning, opened Her heart to Lalita.
Radha sighed, "O Lalita! You made Me believe that I wouuld meet Krsna and submerge in the nectar ocean of His loving embrace. Enticing Me, You took Me from My house and immediately brought Me back. O sakhi! What fault have I made that has denied Me the ocean of nectar?".
She speaks further of the night before, lamenting now that it is over and unsure whether it actually happened.
Lalita replied, "O Radha! Last night, Your union with Krsna made You study the protocols of nirveda(violating the rules of the scriptures). Now, separation from krsna is making You study the protocols of nirveda(despair). Union with Acyuta made You taste the sweetness of His words, lips and form. But separation tortures You like a deadly poison.
In the rapture of love, Vrsabhanunundini failed to grasp Lalita's words. Radhika, hoping to see Her cherished lord in a dream, lay down and fell asleep.