The fifth posture is Phalakasana
Body : Bring left foot back to the plank position. The body is in one straight line. Look between the hands. Elbows are straight.
Breathing : Hold
Mantra: ॐ खगाय नमः (Om Khagaaya Namaha)
Stimulator of the senses
Prostration to Him who moves in the sky
Eyes open when the sun rays touch the face. It is the most precious time to wake up. In Yoga the moment before the sunrise called Brahmamuhurta (Brahma period). Between 4 to 6 AM (depends of the season) the nature is waking up, and this is the best time to do the Sadhana, the spiritual practise and best time to begin the day.
In the Christians monasteries, the monks start the day before 6 AM, in Islam, the first Al Salat ( صلوة)* - Al Soubh is just before sunrise, the Buddhists monks start the meditation at 4 or 5 AM, and maybe you remember, your grandparents came to the filed when the sky had the first flashes of the rays.
Naturaly, the day begins with the Sun.
*the daily prayer
Om Tat Sat
