I think "optimal" macronutrient ratio is a hugely idiosyncratic issue, but here's my experience:

After--like you--seeing a lot of conflicting things from people regarding whether(/which) macronutrient ratio was important for well-being/mood, I decided to do a systematic test of the question as part of a project for a class I took last semester. (I've been paleo and relatively low carb for about a year and a half, so my main manipulation was increasing safe starches during the experimental phases.) It was a single-subject (me, of course) ABAB design study, and I kept careful track of what I ate, took mood/energy measures in the morning, midday and at night, as well as what time I went to bed and got up in the morning (which I do without an alarm), and briefly recorded my most salient social interactions each night. Here were my main findings:

-Two days into the first high-carb phase, my mood got more volatile (i.e., more sensitive to potential negatives in social situations, and more reactive to both positive and negative events, more indignant at potential insults from colleagues), overall mood got more negative. It continued as such until I switched back to high fat. Same thing during the second experimental phase.

-Starting the first night after I entered the first high-carb phase and continuing throughout, I slept a little longer (~30 minutes on average) than during the high-fat baseline, but felt more groggy in the morning than in the baseline condition. I thought this finding was pretty interesting, given that I was really just taking sleep measures as a control variable--I didn't expect it to vary with macronutrient ratio at all.

-I wasn't consciously manipulating caloric intake, but it spontaneously increased by approximately 200 calories a day in the high carb condition (= lower satiety).

Obviously, this doesn't represent gold-standard science or anything (not blind, yadda yadda), but I found it to be a pretty enlightening experience.

Bottom line: personally, higher carb makes me neurotic.

When I was VLC (less than 20g/day), I felt horrible. I thought it was just "carb-flu" but it never went away. I was consistently tired, moody, irritable, no energy, and couldn't concentrate. I reintroduced sweet potatoes and started eating more veggies and now I feel so much better. I alternate low/high carbs. Some days I'll have less than 30g, but today I had about 140g (which is because I went on a really long run).
I always eat my veggies with a big chunk of meat and cooked in fat. So most days I would say my meals are almost equally balanced macro-wise. Higher carb actually keeps me full longer and since it's all veggies (starchy and non-starchy) anyway, it makes my meals more varied and delicious.

Paul Jaminet suggests in The Perfect Health Diet (if you're not familiar, it's not exactly paleo but very much based on evolutionary diet principles like primal and so on--see here: http://perfecthealthdiet.com/?page_id=8) that a certain amount of carbohydrates (up to 150g) are necessary for optimal nervous system functioning. Glucose is the preferred fuel for the brain and nervous tissue, though not the rest of the body. Hence, the optimal source for these carbohydrates is not fruit (due to high amounts of fructose) but rather what he calls "safe starches," like sweet potatoes and rice--though not any other grains. I feel better when I eat moderate amounts of these, keeping below the 150g mark.

Oh, and that 150g number should not count fiber carbs, since soluble fiber is converted into short-chain fatty acids in the gut and insoluble fiber simply passes through.

I tend to agree, but I have also noticed (and read) that carbohydrates over a certain amount (especially without plentiful protein and fat) destabilize mood. It seems there is an ideal range between the two extremes.

I wouldn't make any inferences about carb levels with the sleep dep also going on. In my N=1, my mood is always better with lower carb, especially in the evenings.

Dr. Amen touches on this in one of his videos (much of his nutritional ideas are CW based, so I tend to take them with a grain of salt usually), but his piece about the different kinds of depression and anxiety struck me, some varieties respond better to VLC (I believe if there was low function in the pre-frontal cortex that was the way to go), but if you have low activity in other areas higher carbs helps.

IMO it depends on the individuals ability to process carbohydrates properly. I am prediabetic. Too much carb set me up for blood sugar swings and mood swings. I feel better right after a meal, and very crabby when blood sugar drops later if I ate too much carbs.

If you are underweight you are probably not prediabetic or insulin resistant. You might be one of those people who needs more carbs, in a nice low GI load form.

The way to tell is to keep a food and mood diary. And consider other possible factors that could influence mood. Sleep is certainly a big factor.

Alcohol is a carb. Candy bars are mostly carbs (full of sugar). Soft drinks are mostly carbs (high fructose corn syrup).

All of these give you a rush, even a shot of energy, and make you feel better. All make people grumpy when they are deprived of them (ever see someone with a sweet tooth not get their Coke or candy bar?)

If these forms of carbs have an addictive quality, it's reasonable the carbs in bread and such also have an addictive quality. Which implies there are also withdrawal symptoms associated with restricting bread carbs.

Last I checked, it was estimated that about 15-20% of the typical American's calories came from high fructose corn syrup. Not sugar in general, or carbs in general, but from one thing--high fructose corn syrup.

Maybe you bad mood is from sugar withdrawals.

I have only been Paleo for about 6 weeks, so my answer might be limited, but...

At the beginning, I was naturally eating very low carb and ended up very moody, especially after work and I was snapping at my husband. Neither of us were particularly happy. I started eating a little more fruit, thereby increasing my carbs, and emotionally I felt a lot better. My weight loss has slowed a bit, but I'll take that over being in a constant argument with the husband.