The Compendium of Caraka 1.24.39

1.24.39

meghasaṅkāśamākāśamāvṛtaṃ vā tamoghanaiḥ/
paśyaṃstamaḥ praviśati cirācca pratibudhyate//

Seeing the sky resembling clouds or enveloped in dense darkness, / he enters darkness and awakens after a long time;