Does it take a while to get over the effects of twilight anesthesia for a colonoscopy?

Mac anesthesia : Without any other health issues related to the metabolism of the medications, you should generally feel back to normal within a few hours depending on the agents that are used and certainly after 24 hours.

Sedation: Typical medications used for colonoscopy are Midazolam (versed), fentanyl (sublimaze) and Propofol (diprivan). While other medications are used, these are usually the most common. All have very short half-lives and clinical effects are usually gone within 24 hours. I am not aware of longer term effects if these are similar to the medications you received during your procedure.

Depends on type: If the anesthetic is given by an anesthesiologist they would usually use a very short acting anesthetic agent. If the sedation is done by the GI doctor they tend to use a longer lasting agent. In either case you should be clear headed after a few hours.