Yes, the soul does depart from the body when one is asleep, and returns by the permission of Allah:
اللَّهُ يَتَوَفَّى الأَنْفُسَ حِينَ مَوْتِهَا وَالَّتِي لَمْ تَمُتْ
فِي مَنَامِهَا فَيُمْسِكُ الَّتِي قَضَى عَلَيْهَا الْمَوْتَ وَيُرْسِلُ
الأُخْرَى إِلَى أَجَلٍ مُسَمًّى إِنَّ فِي ذَلِكَ لآيَاتٍ لِقَوْمٍ
Surat Azamar Ayah 42
The above verse, is proof that when we die the smaller death (sleep), and Allah takes our souls, and we are free to roam among (الملأ الأعلى). And when our times are up Allah keeps our souls, and when it is not up yet, he lets us return to our bodies until our time.
It is also said that when one is asleep, souls meet together and get to know each other. It is also said that when sleeps, the soul leaves the body, and this is why we see dreams.
Source: Tafseer Ibn Katheer, Tafseer Atabari, Tafseer Al baghawee