Shiva Purana
सुश्वासेन सुशय्यायां योगं युंजीत योगवित् ॥ दीपं विनांधकारे तु प्रजाः सुप्तेषु धारयेत् ॥ २४॥
The knower of Yoga shall practise it taking breath normally sitting on a good bed. If he practises in darkness he shall not keep any lamp. He shall practise when people are asleep.
english translation
suzvAsena suzayyAyAM yogaM yuMjIta yogavit ॥ dIpaM vinAMdhakAre tu prajAH supteSu dhArayet ॥ 24॥
hk transliteration by Sanscript