Preventing Tangles

Avoiding tangles is one of the main benefits of putting your hair in a silk yarn scarf at night. As you sleep, your head tosses and shifts throughout the night, and hair also gets matted on the blanket. This can lead to some serious tangles and mats in your hair, which in turn can cause breakage when you attempt to comb them out in the morning.
Nighttime Dryness

Dry hair can cause damage and weaken hair, making it more susceptible to breakage, and giving it a lackluster look, which is why you should also wear a silk yarn scarf at night. Many of your common pillowcase fabrics can pull moisture and essential oils your hair needs out of hair, leaving it dryer and more brittle come morning. To prevent this, you can wear a head silk scarf and sleep on a satin pillowcase, as satin draw moisture in as much as other fabrics will.
Breakage At Night

While tangles can cause breakage in the morning, sleeping with your hair unwrapped can also cause breakage. A common cause is the fabric of your pillowcase, commonly cotton fabrics, which hair can get caught on and subsequently break as you move around at night. Your hair may also get wrapped or entangled in your pajamas, if it is past your shoulders or in your arms and hands as you sleep. Keeping it wrapped up can prevent nighttime breakage considerably.