This article is 5 years old, but I thought it might help http://www.veterinarypartner.com/Content.plx?A=3189 See excerpts (out of context) below
Waking at night may occur for reasons other than cognitive dysfunction, such as pain or discomfort. Dogs who are feeling discomfort may pace, pant, vocalize or be restless at night but may not show any physical limitations during the day. The effects of pain or sore muscles may be more noticeable to the dog at night.
Melatonin may help create a normal nighttime sleeping cycle. This supplement should be given at bed time on a regular basis. Combined with a predictable nighttime routine, it can help create a normal sleep pattern.
Pharmacological Treatments
Sometimes medications may be helpful to induce sleep. Benzodiazepines (anti-anxiety medications) such as diazepam (Valium), alprazolam (Xanax), or oxazepam (Serax) may be given. These medications are relatively quick acting but don’t last long so administration must be timed carefully. Medication should be combined with other recommendations described above.
Generalized anxiety may be reduced with medications such as SSRI’s or TCA’s but these medications require many weeks before positive effects are seen. Cognitive dysfunction symptoms may be reduced with selegiline (Anipryl), which when given in the morning may help to keep the dog more alert and active during the daytime. Old age onset of anxiety may reflect the additive effect of lifelong learning or be a sign of progressive decline from cognitive dysfunction.
Expected Outcome
Nighttime waking may be caused by medical or behavioral changes common in senior dogs. Often these problems may be managed and good sleeping patterns can be re-established, though many of the underlying conditions may be persistent and worsen with age. Quick intervention is important since undesirable habits may form quickly and people may become frustrated when they sleep deprived.
