Apparatus for determining sleep staging

• US 6,157,857 A
• Filed: 12/01/1998
• Issued: 12/05/2000
• Est. Priority Date: 07/24/1998
• Status: Expired due to Fees

• Current Assignee: Wilfried Dimpfel
• Original Assignee: Wilfried Dimpfel
• Inventors: Dimpfel, Wilfried
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US09/203,617
• Time in Patent Office: 735 Days
• Field of Search: 600/544, 600/26, 600/545
• US Class Current: 600/544
• CPC Class Codes: A61B 5/374 Detecting the frequency distribution of signals, e.g. detecting delta, theta, alpha, beta or gamma waves
• CPC Class Codes: A61B 5/4821 Determining level or depth of anaesthesia A61B5/1106 takes precedence
• CPC Class Codes: A61B 5/7253 characterised by using transforms
• CPC Class Codes: A61B 5/7257 using Fourier transforms

Abstract

Small bandwidth frequency ranges are disclosed for frequency transformation and processing of EEG signals for determining sleeping staging with a sleep staging index (S_F) in which a frequency transformation of a time domain EEG signal from an EEG measuring device is supplied in a plurality of sub-band frequency ranges a, b, and c. Processing of the frequency domain transformed data is performed which ascertains values A, B, and C representative of the frequency range a from 4.75 to 6.75 Hz, the frequency range b from 12.75 to 18.5 Hz, and the frequency range c from 18.75 to 35.0 Hz or representative of least two of said frequency ranges and determines therefrom a sleep staging index S_F.

Claims

1. An apparatus for determining sleep staging comprising:

a transformation means to which an output signal (EEG(t)) of an EEG measuring device is supplied and which transforms the supplied EEG signal into a frequency range comprising a plurality of sub-bands including frequency ranges a, b, and c; and

a processing means to which the EEG signal (EEG(f)) transformed into the frequency range is supplied from said transformation means and which ascertains values A, B and C representative of the frequency range a from 4.75 to 6.75 Hz, the frequency range b from 12.75 to 18.5 Hz and the frequency range c from 18.75 to 35.0 Hz or representative of least two of said frequency ranges and determines therefrom a sleep staging index S_F.

2. An apparatus according to claim 1, wherein

said processing means determines said sleep staging index SF as a quotient of the sum of said representative values A and B and said representative value C ##EQU2##

3. An apparatus according to claim 2, wherein said processing means ascertains said representative values A, B and C by integration of the EEG signal in the frequency range.

4. An apparatus according to claim 2, wherein

said processing means ascertains said representative values A, B and C by averaging the EEG signal in the frequency range.

5. An apparatus according to claim 4, wherein

said transformation means transforms the supplied EEg signal (EEG(t)) into the frequency range by means of a fast fourier transformation (FFT).