I'll echo that this is really something to talk in depth with, with your provider.

That being said, I can relay what I've been told by providers along with the anecdotal.

Any antidepressant is going to need to "build up" in your system to keep you feeling better. But any pill is going to have a cycle through the day. You take it, and it needs time to get that pill taken up from your digestive tract. Towards the end of your dosage, the levels will dip slightly.

If you take it when you wake up, you're having that uptake process happen while you're trying to get going in the morning. If you take it before bed, by the time you wake up, the dosage is going to be stable. That stability will last through most people's normal day, when they need the effects the most. Your two times when the support of the medication are the weakest will be when you (theoretically) have the least external stressors, which is while sleeping.

Secondarily, bedtime rituals are easier to remember because there's no need to rush around getting ready for the day, leading to better compliance with stable dosage. You fall into the habit of bedtime, and there's less to interrupt that patterm.

Now, my personal experience is that taking the pills before bed is better because the affect on dreams is better. SSRIs are notorious for causing dream changes. I'm already hyperphanstastic (extra vivid dreams and mental imagery). If I take my dose in the morning, then I'm at the low point of the dose when sleeping, which tends to cause less pleasant dreams. Since the kind of dreams I have when I'm not on an antidepressant tend to be the sort you don't want, there's no way in hell I'm doing a morning dose as the norm. You really, really don't want the kind of nightmares I have with the hyper vividness I dream in.

Obviously, that's not going to be the case for everyone, but it is true that most people will have less dream disturbances if the take their dose before bed rather than in the morning. It's that gradual uptake minimizing the effects of the meds on dreams, and avoiding the disturbances that can be caused when a dose is falling off.

There's other little things as well, though they tend to be individual. An example of that is pain relief. If that's one of the effects you take them for, the pain reduction of a fresh dose is typically more useful while sleeping, and during the early part of your day.