Donna And Doc Hayward's Hair In The Pilot

In the Twin Peaks pilot, William and Donna Hayward's hair seems to change throughout the episode.

In Donna's case, her hair appears to grow and recede in length and change from curly to straight. Doc's hair changes color and texture. 

Gray with faint touches of blonde, slightly thicker.

His hair appears a little blonder, wavier.

Grayish-black.

As for Donna

Chin-length and curly.

Later in the day, her hair appears shorter, curls tighter.

Relaxed and straight.

Shorter again. Straight. It appears darker.

Lighter, longer, and straight.

Lighter and voluminous. Longer again.