POWER OF ATTORNEY


      I, the undersigned, hereby authorize and designate Anne Marie
Cook (SVP, General Counsel), Kimi Iguchi (Chief Financial Officer),
Erin Lanciani (SVP, People and Organizational Strategy), and Jennifer
Fitzpatrick (Vice President, Corporate Counsel) for as long as they
remain employees of Sage Therapeutics, Inc., and Laurie Burlingame of
Goodwin Procter, each acting singly, or their successors in role, to
take the following actions, acting as my agent and attorney-in-fact,
with full power of substitution:

          (1)  to prepare and sign on my behalf any Form 3, Form 4 or
Form 5 pursuant to Section 16 of the Securities Exchange Act of 1934,
as amended, and to file the same with the Securities and Exchange
Commission, NASDAQ, NYSE, and each stock exchange on which shares of
Common Stock or other securities of Sage Therapeutics, Inc. are
listed, as required by law;

          (2)  to prepare and sign on my behalf any Form 144
pursuant to the Securities Act of 1933, as amended, and to file the
same with the Securities and Exchange Commission, NASDAQ, NYSE, and
each stock exchange on which shares of Common Stock or other
securities of Sage Therapeutics, Inc. are listed, as required by law;
and

          (3)  take any other action necessary or proper in
connection with the foregoing.

      Unless earlier revoked under the next sentence, this Power of
Attorney shall remain in effect as long as I am an executive officer
or director of Sage Therapeutics, Inc., and shall not be affected by
my subsequent disability or incompetence.  I may revoke this Power of
Attorney by written notice delivered, in person or by nationally
recognized courier, to the attention of the SVP, General Counsel of
Sage Therapeutics, Inc.




                    /s/ Anne Marie Cook
		    ___________________________________________________
                    (Signature of Executive Officer or Director)


                    Name:  Anne Marie Cook

                    Date:    12/13/2018