It depends what your ultimate goal is in professional aviation. Many airlines ask prospective employees, in addition to having a 1st class medical, whether or not the applicant holds a waiver for that 1st class medical. In this case, it is better to get a "letter of competence" which authorizes an AME to issue an unrestricted first class medical based on previous demonstrated ability to see colors.
The other alternative is a SODA (Statement Of Demonstrated Ability) which can be obtained by the FAA through any FSDO. This will remove the night flight restriction on your current medical, but may preclude you from employment from airlines that do not hire pilots who hold waivers to their medical certificate. Another negative is that the failure of a signal light test generally results in a permanent restriction on an airman's medical certificate prohibiting night flying and flight by color signal control.
This is why most recommend obtaining a letter of competence instead, since it is not technically obtained through the FAA, and thus no permanent restriction will be imposed on your medical. The most common exam to obtain a letter of competence is a "Farnsworth Lantern test" and can be administered by several civilian examiners.
If you're an AOPA member, I also highly recommend you call them and ask to speak with someone in the medical services department about the various ways to handle the situation. Gary Crump who is the medical director there is a good friend of mine. Hope this helps and best of luck.
