There's a saying "there's a seat for every chair" Unfortunately it has to agree with you. Many paddlers rectify this problem by making a seat that angles up the same way legs go rather than a flat type of seat. If you had a seat that was three feet long and supported you thighs from your butt forward like a strato lounge, your legs would never fall asleap. Most of the time it's because the seat is flat, and short with no upward angle supporting the thighs. It puts pressure on the lower butt area which cuts off the circulation. You'll have to experiment a bit. Also... new paddlers are more prone to this because the fine muscles in their legs and butt have not developed and become conditioned to the paddling position or sport in general.