There is no undressing in these modalities. The changes come from deep within the body systems and ripple out adjustments to the external tissue and bone, so undressing is not necessary.
People tend to get very quiet due to the nature of the way the work addresses the nervous system. It is not uncommon to fall asleep. I tend to be very focused when I work as I am listening to the layers of fascia, bone tissue, fluids and energy. I am evaluating what the body wants to do next, and am encouraging it along the way.
Most people get very relaxed during a session and there is a tendency to fall asleep while the body is resetting. I will often ask the person to stand up to walk about half way through to see how things have changed and what feels different during gravity and movement. I do like to work about 90 minutes if your body as some challenges and complexity.