parakeet spasms

My parakeet is about 8 or 9 years old.  In the last six months, he has had what I guess are spasms.  Usually, they occur at night.  He makes noises as if he is in pain.  It lasts a minute to 30 minutes.

In daytime he is happy, chatters a lot, and occasionally flys around for exercise.  His cage door is always open.  In the last six weeks, the spasms are more frequent, about 1 to 4 per week.

Thanks.

[ireneo]

Have you gone in to check on him, watch his behavior while he's making these noises? If he's having physical spasms as well, something is going on neurologically. Just vocalizing at night could be anything. Does it happen after he's been asleep for a few hours or just shortly after "bedtime?" Has anything changed in his cage or nearby surroundings that could be frightening him?