Amended Statement of Beneficial Ownership


UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No.6)*

SENIOR HOUSING PROPERTIES TRUST
(Name of Issuer)

Common Stock
(Title of Class of Securities)

81721M109
(CUSIP Number)

December 31, 2011
(Date Of Event which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

[x] Rule 13d-1(b)

[ ] Rule 13d-1(c)

[ ] Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

SEC 1745 (3-06)


CUSIP No.81721M109                      13G                    Page 2 of 8 Pages
--------------------------------------------------------------------------------
   1.  NAME OF REPORTING PERSON:
       I.R.S. IDENTIFICATION NO. OF ABOVE PERSON:

       Morgan Stanley
       I.R.S. #36-3145972
--------------------------------------------------------------------------------
   2.  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:

       (a) [ ]

       (b) [ ]
--------------------------------------------------------------------------------
   3.  SEC USE ONLY:

--------------------------------------------------------------------------------
   4.  CITIZENSHIP OR PLACE OF ORGANIZATION:

       The state of organization is Delaware.
--------------------------------------------------------------------------------
   NUMBER OF      5.   SOLE VOTING POWER:
     SHARES            7,554,298
  BENEFICIALLY    --------------------------------------------------------------
    OWNED BY      6.   SHARED VOTING POWER:
      EACH             0
   REPORTING      --------------------------------------------------------------
     PERSON       7.   SOLE DISPOSITIVE POWER:
      WITH:            8,962,136
                  --------------------------------------------------------------
                  8.   SHARED DISPOSITIVE POWER:
                       0
--------------------------------------------------------------------------------
   9.  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
       8,962,136
--------------------------------------------------------------------------------
  10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES:

       [ ]
--------------------------------------------------------------------------------
  11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
       5.5%
--------------------------------------------------------------------------------
  12.  TYPE OF REPORTING PERSON:
       HC, CO
--------------------------------------------------------------------------------


CUSIP No.81721M109                     13G                     Page 3 of 8 Pages
--------------------------------------------------------------------------------
   1.  NAME OF REPORTING PERSON:
       I.R.S. IDENTIFICATION NO. OF ABOVE PERSON:

       Morgan Stanley Investment Management Inc.
       I.R.S.  #13-3040307
--------------------------------------------------------------------------------
   2.  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:

       (a) [ ]

       (b) [ ]
--------------------------------------------------------------------------------
   3.  SEC USE ONLY:

--------------------------------------------------------------------------------
   4.  CITIZENSHIP OR PLACE OF ORGANIZATION:

       The state of organization is Delaware.
--------------------------------------------------------------------------------
   NUMBER OF      5.   SOLE VOTING POWER:
     SHARES            7,554,298
  BENEFICIALLY    --------------------------------------------------------------
    OWNED BY      6.   SHARED VOTING POWER:
      EACH             0
   REPORTING      --------------------------------------------------------------
     PERSON       7.   SOLE DISPOSITIVE POWER:
      WITH:            8,962,136
                  --------------------------------------------------------------
                  8.   SHARED DISPOSITIVE POWER:
                       0
--------------------------------------------------------------------------------
   9.  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
       8,962,136
--------------------------------------------------------------------------------
  10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES:

       [ ]
--------------------------------------------------------------------------------
  11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
       5.5%
--------------------------------------------------------------------------------
  12.  TYPE OF REPORTING PERSON:
       IA, CO
--------------------------------------------------------------------------------


CUSIP No.81721M109                    13G                      Page 4 of 8 Pages
--------------------------------------------------------------------------------

Item 1.     (a)   Name of Issuer:

                  SENIOR HOUSING PROPERTIES TRUST
                  --------------------------------------------------------------
            (b)   Address of Issuer's Principal Executive Offices:

                  TWO NEWTON PLACE
                  255 WASHINGTON STREET
                  NEWTON MA 02458
                  --------------------------------------------------------------

Item 2.     (a)   Name of Person Filing:

                  (1) Morgan Stanley
                  (2) Morgan Stanley Investment Management Inc.
                  --------------------------------------------------------------
            (b)   Address of Principal Business Office, or if None, Residence:

                  (1) 1585 Broadway
                      New York, NY 10036
                  (2) 522 Fifth Avenue
                      New York, NY 10036
                  --------------------------------------------------------------
            (c)   Citizenship:

                  (1) The state of organization is Delaware.
                  (2) The state of organization is Delaware.
                  --------------------------------------------------------------
            (d)   Title of Class of Securities:

                  Common Stock
                  --------------------------------------------------------------
            (e)   CUSIP Number:

                  81721M109
                  --------------------------------------------------------------

Item 3.     If this statement is filed pursuant to Sections 240.13d-1(b) or
            240.13d-2(b) or (c), check whether the person filing is a:

            (a) [ ]  Broker or dealer registered under Section 15 of the Act
                     (15 U.S.C. 78o).

            (b) [ ]  Bank as defined in Section 3(a)(6) of the Act
                     (15 U.S.C. 78c).

            (c) [ ]  Insurance company as defined in Section 3(a)(19) of the Act
                     (15 U.S.C. 78c).

            (d) [ ]  Investment company registered under Section 8 of the
                     Investment Company Act of 1940 (15 U.S.C. 80a-8).

            (e) [x]  An investment adviser in accordance with Section
                     240.13d-1(b)(1)(ii)(E);
                     Morgan Stanley Investment Management Inc.

            (f) [ ]  An employee benefit plan or endowment fund in accordance
                     with Section 240.13d-1(b)(1)(ii)(F);

            (g) [x]  A parent holding company or control person in accordance
                     with Section 240.13d-1(b)(1)(ii)(G);
                     Morgan Stanley

            (h) [ ]  A savings association as defined in Section 3(b) of the
                     Federal Deposit Insurance Act (12 U.S.C. 1813);

            (i) [ ]  A church plan that is excluded from the definition of an
                     investment company under Section 3(c)(14) of the
                     Investment Company Act of 1940 (15 U.S.C. 80a-3);

            (j) [ ]  Group, in accordance with Section 13d-1(b)(1)(ii)(J).


CUSIP No.81721M109                   13-G                      Page 5 of 8 Pages
--------------------------------------------------------------------------------

Item 4.    Ownership as of December 31, 2011.*

           (a) Amount beneficially owned:
           See the response(s) to Item 9 on the attached cover page(s).

           (b) Percent of Class:
           See the response(s) to Item 11 on the attached cover page(s).

           (c) Number of shares as to which such person has:

              (i)   Sole power to vote or to direct the vote:
                    See the response(s) to Item 5 on the attached cover page(s).

              (ii)  Shared power to vote or to direct the vote:
                    See the response(s) to Item 6 on the attached cover page(s).

              (iii) Sole power to dispose or to direct the disposition of:
                    See the response(s) to Item 7 on the attached cover page(s).

              (iv)  Shared power to dispose or to direct the disposition of:
                    See the response(s) to Item 8 on the attached cover page(s).

Item 5.    Ownership of Five Percent or Less of a Class.

           Not Applicable

Item 6.    Ownership of More Than Five Percent on Behalf of Another Person.

           Not Applicable

Item 7.    Identification and Classification of the Subsidiary which Acquired
           the Security Being Reported on By the Parent Holding Company.

           See Exhibit 99.2

Item 8.    Identification and Classification of Members of the Group.

           Not Applicable

Item 9.    Notice of Dissolution of Group.

           Not Applicable

Item 10.   Certification.

           By signing below I certify that, to the best of my knowledge and
           belief, the securities referred to above were acquired and are
           held in the ordinary course of business and were not acquired and
           are not held for the purpose of or with the effect of changing or
           influencing the control of the issuer of the securities and were
           not acquired and are not held in connection with or as a participant
           in any transaction having that purpose or effect.

*  In Accordance with the Securities and Exchange Commission Release
No. 34-39538 (January 12, 1998) (the "Release"), this filing reflects the
securities beneficially owned, or that may be deemed to be beneficially owned,
by certain operating units (collectively, the "MS Reporting Units") of Morgan
Stanley and its subsidiaries and affiliates (collectively, "MS").  This filing
does not reflect securities, if any, beneficially owned by any operating units
of MS whose ownership of securities is disaggregated from that of the MS
Reporting Units in accordance with the Release.


CUSIP No.81721M109                  13-G                      Page 6 of 8 Pages
--------------------------------------------------------------------------------

                                  Signature.


After reasonable inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.


Date:       February 8, 2012

Signature:  /s/ Michael Lees
            --------------------------------------------------------------------

Name/Title: Michael Lees/Authorized Signatory, Morgan Stanley
            --------------------------------------------------------------------
            MORGAN STANLEY


Date:       February 8, 2012

Signature:  /s/ Mary Ann Picciotto
            --------------------------------------------------------------------

Name/Title: Mary Ann Picciotto/Chief Compliance Officer, Morgan Stanley
                                Investment Management Inc.
            --------------------------------------------------------------------
            MORGAN STANLEY INVESTMENT MANAGEMENT INC.




EXHIBIT NO.                         EXHIBITS                                PAGE
-----------                        ----------                               ----

   99.1                       Joint Filing Agreement                          7

   99.2                       Item 7 Information                              8


*  Attention. Intentional misstatements or omissions of fact constitute federal
criminal violations (see 18 U.S.C. 1001).


CUSIP No.81721M109                   13-G                      Page 7 of 8 Pages
--------------------------------------------------------------------------------

                       EXHIBIT NO. 99.1 TO SCHEDULE 13G
                            JOINT FILING AGREEMENT
              ---------------------------------------------------


                               February 8, 2012
              ---------------------------------------------------


              MORGAN STANLEY and MORGAN STANLEY INVESTMENT MANAGEMENT INC.,

              hereby agree that, unless differentiated, this

              Schedule 13G is filed on behalf of each of the parties.


           MORGAN STANLEY

           BY: /s/ Michael Lees
           ---------------------------------------------------------------------
           Michael Lees/Authorized Signatory, Morgan Stanley

           MORGAN STANLEY INVESTMENT MANAGEMENT INC.

           BY: /s/ Mary Ann Picciotto
           ---------------------------------------------------------------------
           Mary Ann Picciotto/Chief Compliance Officer, Morgan Stanley
                               Investment Management Inc.


*  Attention. Intentional misstatements or omissions of fact constitute federal
criminal violations (see 18 U.S.C. 1001).


CUSIP No.81721M109                    13-G                     Page 8 of 8 Pages
--------------------------------------------------------------------------------

                                 EXHIBIT NO. 99.2
                                ------------------

                                ITEM 7 INFORMATION


             The securities being reported on by Morgan Stanley as a parent

      holding company are owned, or may be deemed to be beneficially owned, by

      Morgan Stanley Investment Management Inc., an investment adviser in

      accordance with Rule 13d-1(b)(1)(ii)(E) as amended.  Morgan Stanley

      Investment Management Inc. is a wholly-owned subsidiary of Morgan Stanley.