I've noticed that whenever I'm driving at night that at certain points it seems that my car loses power (however it stays on, doesn't cut off), and I notice it whenever I see my lights dim. This phenomenon doesn't happen during the day when I don't have my lights on (Or from what I've observed it doesn't happen)

Here's the Scenario: I'll be driving at night with my lights on, and whenever I'll be cruising (say 45mph) The lights will randomly dim, and I can tell the engine loses power(Doesn't maintain speed and slows down a little), however it only lasts for a split second, (Not longer than 1 sec, maybe .5 a sec.). I'm beginning to think that it's my alternator. Would it be right to suspect that?