Light napper

Anyone else have a baby that just won't nap during the day? My LO is such a light sleeper. Usually she has one good nap (2 hours if I'm really lucky) and maybe 2 more that are usually 45 min long. I usually complain about this but today her naps were 20 minutes long. She had 3 of those. By the end of the day, she was so tired she cried for nearly an hour before she would settle for sleep. I'm hoping it was just a bad day. Any ideas on how to cope or get her to rest for longer period during the day?