How long does it take to deep condition hair?

Deep conditioner is usually left in the hair for 20 minutes and for no longer than 30 minutes. It is not recommended that you leave it in while sleeping or for the whole day, as it stops benefiting your hair after the first half hour and may cause problems like greasiness, making your hair lank and heavy, or even causing hair to fall out if left in too long. Read the instructions on the packaging, as the length of time may vary depending on the product used. The standard 20-minutes is usually just right for achieving hair repair and care.