Genetics can also play a role in oily hair in the morning. If you have a family history of oily hair, then you may be more likely to experience it yourself. In addition, certain hairstyles can contribute to oily hair. For example, if you wear your hair up in a tight bun, it can cause your scalp to produce more oil.
The environment can also contribute to oily hair in the morning. If you live in an area with high humidity, the extra moisture in the air can lead to an increase in oil production. Using certain hair care products can also increase oil production. For example, products with heavy fragrances or those that contain petroleum-based ingredients can increase the production of sebum.