Muskan G.

If yoga is your only workout, aim for at least 20-30 minutes of yoga, 6 days per week. If necessary, you can start with 3 days per week for your first month. As your fitness level increases, you can increase that to 40-70 minutes per day.

But I would suggest to do pranayama atleast for 15min daily.

Yoga asana and pranayama's help to curtail stress, anxiety and improve cellular oxygen levels and blood circulation these in turn help to prevent hair loss. If done on a regular basis they not only prevent hair loss but also repair hair damage and promote hair health and growth. All inversion posses will increase the blood circulation for eg. Sirsasana. 

My favorite yog asana is Sirsasana because it 

• Relieves Stress. 
• Increases Focus.
• Improves Blood Flow To The Eyes. 
• Increases Blood Flow To The Head And Scalp.
• Strengthens Shoulders And Arms. 
• Improves Digestion.

Kriya yoga is a meditation technique of controlling energy through pranayama and meditation, which speeds up the spiritual process of the aspirant. Most practitioners of meditation spend time in self-study and practice until they are ready to be further initiated into the advanced practices of Kriya yoga. Beginning meditators are advised to use a mantra or word in order to focus their attention and progress into deeper meditation sessions.