Yes, it could be.

The hormones in BC pills can make depression worsen, especially in women that have a history of depression.

Do you take any antidepressants? That does help most women with this problem.

Using non hormonal birth control could be an option too.

The hormones in Seasonique are ethinyl estradiol(estrogen, 30 mcg) and levonorgestrel( progestin, 0.15 mg). Levonorgestrel is a potent progestin, which is why it occurs in such a low dose. I'm most familiar with norethindrone and it's kind of the guideline for progestins, so I'll compare it. 0.15 mg of levonorgestrel is equal to 0.795 mg of norethindrone, which is kind of a high dose of progestin. Higher progestin is associated with depression, so you might want to switch to a pill with a lower concentration of progestin (beware that different progestins have different strengths, so a lower dose doesn't mean a lower concentration). Some pills you might want to switch to, with similiar estrogen content, are (keep in mind yours has an equivalent to 0.795 mg of norethindrone):
Femcon Fe (35 mcg estrogen, 0.4 mg norethindrone)
Brevicon (35 mcg estrogen, 0.5 mg norethindrone)
Modicon (same as above)
Ortho-Cyclen (35 mcg estrogen, 0.25 mg norgestimate which equates to .325 norethindrone)

Avoid triphasic pills (pills that have a different amount of hormones in each week) as these can also cause depression.

A lower progestin potency may cause increased risk of breakthrough bleeding, but give it a shot.

I have used alesse 28 for at least 5 years! and i have no problems with it! and further more i haven't gained weight.. I lost weight instead and no pimples either! and some of my friends are taking it just to loose weight as well.. and now I can't find it... can anybody point me to where I can get alesse? I switch to a different brand and i was all of a sudden emotional and I gained weight! (it's Sronyx levonorgestrel) supposedly my doctor said that it's generic of alesse.. I guess that's what most doctors say to their patients when requested with Alesse. I called Wyeth as well and asked them (I didn't want to just buy online as far as drugs are concerned.. kind of scared... But Wyeth said they sold teh product to Akrimax, I went to their site but I guess they have repackaged Alesse.... and not sure if they do have the same ingredients. Does anyone knows where I can get Alesse or can recommend a good BCP from their experience??? Thanks!