Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Gregory T. Ackroyd, M.D.

Sleep Medicine (Psychiatry & Neurology) Physician in Santa Rosa, CA · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1538192984

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Registry record

Entity type Individual (Type 1)

Name Dr. Gregory T. Ackroyd

Credential M.D.

Sex Male

Practice address 585 W College Ave, Santa Rosa, CA, 95401

Phone (707) 525-9616

Fax (707) 526-2358

Enumeration date Jul 9, 2006

Last updated in NPPES Oct 14, 2021

Taxonomy & licenses

2084S0012X Sleep Medicine (Psychiatry & Neurology) Physician Allopathic & Osteopathic Physicians · License A84348 (CA) Primary

2084N0400X Neurology Physician Allopathic & Osteopathic Physicians · License A84348 (CA) Secondary

MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

Other identifiers

Identifier	Type	State	Issuer
5901340	Medicaid	NC	-

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

What is the NPI number for Gregory Ackroyd?

The National Provider Identifier (NPI) for Gregory Ackroyd is 1538192984, a Type 1 (individual) record in the CMS NPPES registry.

Where does Gregory Ackroyd practice?

The practice location on file with NPPES is in Santa Rosa, CA. Providers can have multiple locations; NPPES lists the primary practice address.

Other providers at this practice address

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2021-10-14.