Hi and welcome to the Chiari forum.
Sleep is one of the major issues we all have and complain about as we need to sleep or we can be more our of sorts...I feel it affects our balance more when we do not sleep....so it is something to look at.
Sleep apnea affects many with Chiari so, u may want a sleep study done to rule this related condition out.
Find a true Chiari specialist and have more testing done to rule out other related and non related conditions that could be affecting u.
We do have a list of Drs in the Health Pages for u to use as a tool to start researching Drs as the list is NOT a referral nor an endorsement for those listed.
http://www.medhelp.org/health_pages/list?cid=186
Ask ur Dr about antihistamines....since my Dr started me on them I sleep much better....I also had decompression surgery for Chiari....but sleep was still an issue....going to bed at the same time every night helps too....
Keep us posted on ur Dr search and testing issues/results.