Pernix Sleep SC 13D/A Somaxon Pharmaceuticals / MPM BIOVENTURES III-QP ownership change

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 13D

UNDERTHE SECURITIES EXCHANGE ACTOF 1934

(Amendment No. 3)*

Somaxon Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

834453 10 2

(CUSIP Number)

LUKE EVNIN

MPM ASSET MANAGEMENT

THE JOHN HANCOCK TOWER

200 CLARENDON STREET, 54^TH FLOOR

BOSTON, MASSACHUSETTS 02116

TELEPHONE: (617) 425-9200

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

July 18, 2012

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

* 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 disclosures provided in a prior cover page.

The information required on 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 theNotes).

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons MPM BioVentures III-QP, L.P
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) WC
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 1,064,125(2)
		8.	Shared Voting Power 0
		9.	Sole Dispositive Power 1,064,125(2)
		10.	Shared Dispositive Power 0
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,064,125(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 2.2%(3)
14.	Type of Reporting Person (see instructions) PN

(1) This Schedule is filed by MPM BioVentures III-QP, L.P. (“BV III QP ”), MPM BioVentures III, L.P. (“BV III”), MPM BioVentures III Parallel Fund, L.P. (“BV III PF”), MPM BioVentures III GmbH & Co. Beteiligungs KG (“BV III KG”), MPM Asset Management Investors 2005 BVIII LLC (“AM LLC”), MPM BioVentures III GP, L.P. (“BV III GP”) and MPM BioVentures III LLC (“BV III LLC” and collectively with BV III QP, BV III, BV III PF, BV III KG, AM LLC and BV III GP, the “MPM Entities”) and Luke Evnin, Ansbert Gadicke, Nicholas Galakatos, Michael Steinmetz, Kurt Wheeler, Nicholas Simon III and Dennis Henner (collectively, the “Listed Persons”). BVIII GP and BVIII LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG. The Listed Persons are Series A members of BV III LLC and managers of AM LLC. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Represents shares of common stock, par value $0.01 per share (the “Common Stock”) issuable pursuant to warrants, which are exercisable within 60 days of the date of this filing.

(3) This percentage is calculated based upon 48,108,251 shares of Somaxon Pharmaceuticals, Inc.’s (the “Issuer’s”) Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act of 1934, as amended (the “Exchange Act”), as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons MPM BioVentures III, L.P
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) WC
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 71,553(2)
		8.	Shared Voting Power 0
		9.	Sole Dispositive Power 71,553(2)
		10.	Shared Dispositive Power 0
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 71,553(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 0.2%(3)
14.	Type of Reporting Person (see instructions) PN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Represents shares of Common Stock issuable pursuant to warrants, which are exercisable within 60 days of the date of this filing.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act of 1934, as amended (the “Exchange Act”), as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons MPM Asset Management Investors 2005 BVIII LLC
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) WC
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 18,848(2)
		8.	Shared Voting Power 0
		9.	Sole Dispositive Power 18,848(2)
		10.	Shared Dispositive Power 0
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 18,848(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 0.0%(3)
14.	Type of Reporting Person (see instructions) 00

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Represents shares of Common Stock issuable pursuant to warrants, which are exercisable within 60 days of the date of this filing.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons MPM BioVentures III Parallel Fund, L.P
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) WC
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 32,144(2)
		8.	Shared Voting Power 0
		9.	Sole Dispositive Power 32,144(2)
		10.	Shared Dispositive Power 0
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 32,144(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 0.1%(3)
14.	Type of Reporting Person (see instructions) PN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Represents shares of Common Stock issuable pursuant to warrants, which are exercisable within 60 days of the date of this filing.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons MPM BioVentures III GmbH & Co. Beteiligungs KG
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) WC
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization Germany
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 89,923(2)
		8.	Shared Voting Power 0
		9.	Sole Dispositive Power 89,923(2)
		10.	Shared Dispositive Power 0
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 89,923(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 0.2%(3)
14.	Type of Reporting Person (see instructions) PN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Represents shares of Common Stock issuable pursuant to warrants, which are exercisable within 60 days of the date of this filing.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons MPM BioVentures III GP, L.P
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) WC
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 0
		8.	Shared Voting Power 1,257,745(2)
		9.	Sole Dispositive Power 0
		10.	Shared Dispositive Power 1,257,745(2)
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,257,745(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 2.6%(3)
14.	Type of Reporting Person (see instructions) PN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Consists of 1,064,125 shares of Common Stock issuable upon exercise of warrants held by BV III QP; 71,553 shares of Common Stock issuable upon exercise of warrants held by BV III; 32,144 shares of Common Stock issuable upon exercise of warrants held by BV III PF; and 89,923 shares of Common Stock issuable upon exercise of warrants held by BV III KG. The warrants listed above are exercisable within 60 days of the date of this filing. BV III GP and BV III LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons MPM BioVentures III LLC
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) WC
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 0
		8.	Shared Voting Power 1,257,745(2)
		9.	Sole Dispositive Power 0
		10.	Shared Dispositive Power 1,257,745(2)
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,257,745(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 2.6%(3)
14.	Type of Reporting Person (see instructions) OO

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Consists of 1,064,125 shares of Common Stock issuable upon exercise of warrants held by BV III QP; 71,553 shares of Common Stock issuable upon exercise of warrants held by BV III; 32,144 shares of Common Stock issuable upon exercise of warrants held by BV III PF; and 89,923 shares of Common Stock issuable upon exercise of warrants held by BV III KG. The warrants listed above are exercisable within 60 days of the date of this filing. BV III GP and BV III LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons Luke Evnin
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) OO
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization United States
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 0
		8.	Shared Voting Power 1,276,593(2)
		9.	Sole Dispositive Power 0
		10.	Shared Dispositive Power 1,276,593(2)
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,276,593(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 2.6%(3)
14.	Type of Reporting Person (see instructions) IN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Consists of 1,064,125 shares of Common Stock issuable upon exercise of warrants held by BV III QP; 71,553 shares of Common Stock issuable upon exercise of warrants held by BV III; 32,144 shares of Common Stock issuable upon exercise of warrants held by BV III PF; 89,923 shares of Common Stock issuable upon exercise of warrants held by BV III KG; and 18,848 shares of Common Stock issuable upon exercise of warrants held by AM LLC. The warrants listed above are exercisable within 60 days of the date of this filing. BV III GP and BV III LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG. The Reporting Person is a Series A member of BV III LLC and a manager of AM LLC.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons Ansbert Gadicke
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) OO
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization United States
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 0
		8.	Shared Voting Power 1,276,593(2)
		9.	Sole Dispositive Power 0
		10.	Shared Dispositive Power 1,276,593(2)
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,276,593(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 2.6%(3)
14.	Type of Reporting Person (see instructions) IN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Consists of 1,064,125 shares of Common Stock issuable upon exercise of warrants held by BV III QP; 71,553 shares of Common Stock issuable upon exercise of warrants held by BV III; 32,144 shares of Common Stock issuable upon exercise of warrants held by BV III PF; 89,923 shares of Common Stock issuable upon exercise of warrants held by BV III KG; and 18,848 shares of Common Stock issuable upon exercise of warrants held by AM LLC. The warrants listed above are exercisable within 60 days of the date of this filing. BV III GP and BV III LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG. The Reporting Person is a Series A member of BV III LLC and a manager of AM LLC.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons Nicholas Galakatos
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) OO
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization United States
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 0
		8.	Shared Voting Power 1,276,593(2)
		9.	Sole Dispositive Power 0
		10.	Shared Dispositive Power 1,276,593(2)
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,276,593(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 2.6%(3)
14.	Type of Reporting Person (see instructions) IN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Consists of 1,064,125 shares of Common Stock issuable upon exercise of warrants held by BV III QP; 71,553 shares of Common Stock issuable upon exercise of warrants held by BV III; 32,144 shares of Common Stock issuable upon exercise of warrants held by BV III PF; 89,923 shares of Common Stock issuable upon exercise of warrants held by BV III KG; and 18,848 shares of Common Stock issuable upon exercise of warrants held by AM LLC. The warrants listed above are exercisable within 60 days of the date of this filing. BV III GP and BV III LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG. The Reporting Person is a Series A member of BV III LLC and a manager of AM LLC.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons Michael Steinmetz
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) OO
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization United States
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 0
		8.	Shared Voting Power 1,276,593(2)
		9.	Sole Dispositive Power 0
		10.	Shared Dispositive Power 1,276,593(2)
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,276,593(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 2.6%(3)
14.	Type of Reporting Person (see instructions) IN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Consists of 1,064,125 shares of Common Stock issuable upon exercise of warrants held by BV III QP; 71,553 shares of Common Stock issuable upon exercise of warrants held by BV III; 32,144 shares of Common Stock issuable upon exercise of warrants held by BV III PF; 89,923 shares of Common Stock issuable upon exercise of warrants held by BV III KG; and 18,848 shares of Common Stock issuable upon exercise of warrants held by AM LLC. The warrants listed above are exercisable within 60 days of the date of this filing. BV III GP and BV III LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG. The Reporting Person is a Series A member of BV III LLC and a manager of AM LLC.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons Kurt Wheeler
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) OO
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization United States
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 0
		8.	Shared Voting Power 1,276,593(2)
		9.	Sole Dispositive Power 0
		10.	Shared Dispositive Power 1,276,593(2)
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,276,593(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 2.6%(3)
14.	Type of Reporting Person (see instructions) IN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Consists of 1,064,125 shares of Common Stock issuable upon exercise of warrants held by BV III QP; 71,553 shares of Common Stock issuable upon exercise of warrants held by BV III; 32,144 shares of Common Stock issuable upon exercise of warrants held by BV III PF; 89,923 shares of Common Stock issuable upon exercise of warrants held by BV III KG; and 18,848 shares of Common Stock issuable upon exercise of warrants held by AM LLC. The warrants listed above are exercisable within 60 days of the date of this filing. BV III GP and BV III LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG. The Reporting Person is a Series A member of BV III LLC and a manager of AM LLC.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons Nicholas Simon III
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) OO
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization United States
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 0
		8.	Shared Voting Power 1,276,593(2)
		9.	Sole Dispositive Power 0
		10.	Shared Dispositive Power 1,276,593(2)
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,276,593(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 2.6%(3)
14.	Type of Reporting Person (see instructions) IN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Consists of 1,064,125 shares of Common Stock issuable upon exercise of warrants held by BV III QP; 71,553 shares of Common Stock issuable upon exercise of warrants held by BV III; 32,144 shares of Common Stock issuable upon exercise of warrants held by BV III PF; 89,923 shares of Common Stock issuable upon exercise of warrants held by BV III KG; and 18,848 shares of Common Stock issuable upon exercise of warrants held by AM LLC. The warrants listed above are exercisable within 60 days of the date of this filing. BV III GP and BV III LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG. The Reporting Person is a Series A member of BV III LLC and a manager of AM LLC.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

CUSIP No. 834453 10 2 13D

1.	Name of Reporting Persons Dennis Henner
2.	Check the Appropriate Box if a Member of a Group (see instructions) (a)  ¨        (b)  x(1)
3.	SEC USE ONLY
4.	Source of Funds (see instructions) OO
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Item 2(d) or 2(e)  ¨
6.	Citizenship or Place of Organization United States
Number of Shares Beneficially Owned by Each Reporting Person With		7.	Sole Voting Power 0
		8.	Shared Voting Power 1,276,593(2)
		9.	Sole Dispositive Power 0
		10.	Shared Dispositive Power 1,276,593(2)
11.	Aggregate Amount Beneficially Owned by Each Reporting Person 1,276,593(2)
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (see instructions)  ¨
13.	Percent of Class Represented by Amount in Row 11 2.6%(3)
14.	Type of Reporting Person (see instructions) IN

(1) This Schedule is filed by the MPM Entities and the Listed Persons. The MPM Entities and the Listed Persons expressly disclaim status as a “group” for purposes of this Schedule 13D.

(2) Consists of 1,064,125 shares of Common Stock issuable upon exercise of warrants held by BV III QP; 71,553 shares of Common Stock issuable upon exercise of warrants held by BV III; 32,144 shares of Common Stock issuable upon exercise of warrants held by BV III PF; 89,923 shares of Common Stock issuable upon exercise of warrants held by BV III KG; and 18,848 shares of Common Stock issuable upon exercise of warrants held by AM LLC. The warrants listed above are exercisable within 60 days of the date of this filing. BV III GP and BV III LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG. The Reporting Person is a Series A member of BV III LLC and a manager of AM LLC.

(3) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

Explanatory Note:

This Amendment No. 3 to Schedule 13D (this “Schedule 13D/A”) amends and supplements the Schedule 13D previously filed by the undersigned with the Securities and Exchange Commission on July 16, 2009 and amended by Amendment No. 1 filed June 12, 2012 and Amendment No. 2 filed July 17, 2012 (as amended, the “Original Schedule 13D”). This Schedule 13D/A is being filed to report the open market sales of shares of common stock of Somaxon Pharmaceuticals, Inc. (the “Company”) by the MPM Entities.

All capitalized terms not otherwise defined herein shall have the meaning ascribed to the terms in the Original Schedule 13D. The Original Schedule 13D is hereby amended and supplemented as follows and, except as expressly amended below, the Original Schedule 13D remains in full force and effect.

Item 4. Purpose of Transaction

Item 4 of the Original Schedule 13D is hereby amended and supplemented by adding the following paragraph at the end of Item 4:

The MPM Entities sold an aggregate of 1,275,886 shares of Common Stock in open market transactions on July 18, 2012 for aggregate proceeds of $641,756.

Item 5. Interest in Securities of the Issuer

“Item 5 of the Original Schedule 13D is hereby amended and restated in its entirety as follows:

(a) – (b) The following information with respect to the ownership of the common stock of the Issuer by the Reporting Persons is provided as of July 18, 2012:

MPM Entity	Shares Held Directly		Shares Issuable Upon Exercise of Warrants Held Directly(1)		Sole Voting Power		Shared Voting Power		Sole Dispositive Power		Shared Dispositive Power		Beneficial Ownership		Percentage of Class (2)
BV III QP		0		1,064,125		1,064,125		0		1,064,125		0		1,064,125		2.2	%
BV III		0		71,553		71,553		0		71,553		0		71,553		0.2	%
AM LLC		0		18,848		18,848		0		18,848		0		18,848		0.0	%
BV III PF		0		32,144		32,144		0		32,144		0		32,144		0.1	%
BV III KG		0		89,923		89,923		0		89,923		0		89,923		0.2	%
BV III GP(3)		0		0		0		1,257,745		0		1,257,745		1,257,745		2.6	%
BV III LLC(3)		0		0		0		1,257,745		0		1,257,745		1,257,745		2.6	%
Luke Evnin(4)		0		0		0		1,276,593				1,276,593		1,276,593		2.6	%
Ansbert Gadicke(4)		0		0		0		1,276,593		0		1,276,593		1,276,593		2.6	%
Nicholas Galakatos(4)		0		0		0		1,276,593		0		1,276,593		1,276,593		2.6	%
Michael Steinmetz(4)		0		0		0		1,276,593		0		1,276,593		1,276,593		2.6	%
Kurt Wheeler(4)		0		0		0		1,276,593		0		1,276,593		1,276,593		2.6	%
Nicholas Simon III(4)		0		0		0		1,276,593		0		1,276,593		1,276,593		2.6	%
Dennis Henner(4)		0		0		0		1,276,593		0		1,276,593		1,276,593		2.6	%

(1) Comprised of securities exercisable within 60 days of the filing date.

(2) This percentage is calculated based upon 48,108,251 shares of the Issuer’s Common Stock outstanding as of April 9, 2012 as adjusted pursuant to Rule 13d-3(d)(1) promulgated under the Exchange Act, as disclosed in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 10, 2012.

(3) BV III GP and BV III LLC are the direct and indirect general partners of BV III QP, BV III, BV III PF and BV III KG. The securities are held as follows: BV III QP: warrants to purchase 1,064,125 shares of Common Stock; BV III: warrants to purchase 71,553 shares of Common Stock; BV III PF: warrants to purchase 32,144 shares of Common Stock; and BV III KG: warrants to purchase 89,923 shares of Common Stock.

(4) The Reporting Person is a Series A Member of BV III LLC and manager of AM LLC. The securities are held as follows: BV III QP: warrants to purchase 1,064,125 shares of Common Stock; BV III: warrants to purchase 71,553 shares of Common Stock; BV III PF: warrants to purchase 32,144 shares of Common Stock; BV III KG: warrants to purchase 89,923 shares of Common Stock; and AM LLC: warrants to purchase 18,848 shares of Common Stock.

(c) The Reporting Persons sold the following shares of Common Stock in the open market during the sixty days immediately preceding the date of the filing of this Schedule 13D/A and, except as set forth below, the Reporting Persons have not engaged in any transactions in the Common Stock during such time period:

MPM Entity	Date of Transaction		Number of Shares Sold		Price Per Share
BV III QP		7/18/12		1,063,520	$	0.51
BV III		7/18/12		71,513	$	0.51
BV III PF		7/18/12		32,125	$	0.51
BV III KG		7/18/12		89,872	$	0.51
AM LLC		7/18/12		18,856	$	0.51

(d) Not applicable.

(e) Not applicable.

The information provided and incorporated by reference in Item 3 is hereby incorporated by reference.

Item 7. Material to Be Filed as Exhibits

Item 7 of the Original Schedule 13D is hereby supplemented by adding the following in appropriate order:

C. Agreement regarding filing of joint Schedule 13D.

SIGNATURES

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.

Dated: July 20, 2012

MPM BIOVENTURES III, L.P.		MPM BIOVENTURES III-QP, L.P.
By:	MPM BioVentures III GP, L.P.,	By:	MPM BioVentures III GP, L.P.,
	its General Partner		its General Partner
By:	MPM BioVentures III LLC,	By:	MPM BioVentures III LLC,
	its General Partner		its General Partner
By:	/s/ Luke Evnin	By:	/s/ Luke Evnin
	Name: Luke Evnin		Name: Luke Evnin
	Title: Series A Member		Title: Series A Member
MPM BIOVENTURES III PARALLEL FUND, L.P.		MPM BIOVENTURES III GMBH & CO. BETEILIGUNGS KG
By:	MPM BioVentures III GP, L.P.,	By:	MPM BioVentures III GP, L.P.,
	its General Partner		in its capacity as the Managing Limited Partner
By:	MPM BioVentures III LLC,	By:	MPM BioVentures III LLC,
	its General Partner		its General Partner
By:	/s/ Luke Evnin	By:	/s/ Luke Evnin
	Name: Luke Evnin		Name: Luke Evnin
	Title: Series A Member		Title: Series A Member
MPM ASSET MANAGEMENT INVESTORS 2005 BVIII LLC		MPM BIOVENTURES III GP, L.P.
By:	/s/ Luke Evnin	By:	MPM BioVentures III LLC,
	Name: Luke Evnin		its General Partner
	Title: Manager
		By:	/s/ Luke Evnin
			Name: Luke Evnin
			Title: Series A Member
MPM BIOVENTURES III LLC
By:	/s/ Luke Evnin		/s/ Luke Evnin
	Name: Luke Evnin		Luke Evnin
	Title: Series A Member
	/s/ Ansbert Gadicke		/s/ Nicholas Galakatos
	Ansbert Gadicke		Nicholas Galakatos
	/s/ Michael Steinmetz		/s/ Kurt Wheeler
	Michael Steinmetz		Kurt Wheeler
	/s/ Nicholas Simon III		/s/ Dennis Henner
	Nicholas Simon III		Dennis Henner

The original statement shall be signed by each person on whose behalf the statement is filed or his authorized representative. If the statement is signed on behalf of a person by his authorized representative (other than an executive officer or general partner of the filing person), evidence of the representative’s authority to sign on behalf of such person shall be filed with the statement: provided, however, that a power of attorney for this purpose which is already on file with the Commission may be incorporated by reference. The name and any title of each person who signs the statement shall be typed or printed beneath his signature.

Attention: Intentional misstatements or omissions of fact

constitute Federal criminal violations (See 18 U.S.C. 1001)

EXHIBIT INDEX

C. Agreement regarding filing of joint Schedule 13D.