Natyashastra
उत्तानितमुखं चैव स्रस्तमुक्तकरं तथा । समं नाम प्रसुप्तस्य स्थानकं संविधीयते ॥ २३०॥
Lying on the back with the face turned upward, and the arms loosened and relaxed— this posture is called *Sama* and is to be used to represent someone in deep sleep.
english translation
uttAnitamukhaM caiva srastamuktakaraM tathA । samaM nAma prasuptasya sthAnakaM saMvidhIyate ॥ 230॥
hk transliteration by Sanscript