I too have experienced the same things that "a2gupta" has: anxiety, depression, mood swings, fogginess, low boiling point, poor sleeping, low self-esteem and yes even suicidal thoughts. I have been on Singular since Sept 2003. I just had that confirmed by my Dr.'s office. I have been on so many anti-depressant medications since taking Singulair and it is well documented. No wonder they have never worked, it is because I still remained on Singulair. Well no longer.
I am 38 as well and have had the exact same symptoms with the exact same thoughts of hormonal changes. Stumbled across your posting yesterday, immediately stopped the Singulair and the anti-depressant, can't tell you how fabulous I feel today. Thank you so much.