प्रातर्मध्यन्दिने सायं अर्धरात्रे च कुम्भकान् । शनैरशीतिपर्यन्तं चतुर्वारं समभ्यसेत् ॥ २.११ ॥

prātarmadhyandine sāyaṃ ardharātre ca kumbhakān । śanairaśītiparyantaṃ caturvāraṃ samabhyaset ॥ 2.11 ॥

Kumbhakas should be performed gradually, four times during the day i.e., in the morning, at noon, in the evening and at midnight, with the Kumbhaka lasting 80 pala (a unit of time, 80 pala or seconds = one Kumbhaka and altogether this totals 320 seconds per day).