** Drugmaker Axsome Therapeutics' AXSM.O shares fall 3.1% to $113 premarket

** AXSM says it will narrow the focus of a late-stage study of its depression drug after it did not show statistically significant improvement in the overall group of patients

** However, it helped reduce symptoms in some patients with major depressive disorder who also suffered from excessive daytime sleepiness (EDS), a common symptom of MDD

** AXSM plans to start a larger late-stage study of the drug in MDD patients with EDS this year

** Solriamfetol is already approved in the U.S. to improve wakefulness in adults with excessive sleepiness from sleep disorders, narcolepsy and sleep apnea

** Brokerage Truist Securities says solriamfetol could potentially address the MDD demographic who may be complementary to those addressed by Auvelity, AXSM's FDA-approved treatment for MDD

** As of last close, AXSM has risen 46% in the past 12 months

(Reporting by Siddhi Mahatole)

((siddhi.mahatole@thomsonreuters.com))