Alarm upon detection of impending sleep state

• US 20010031930A1
• Filed: 12/15/2000
• Published: 10/18/2001
• Est. Priority Date: 12/19/1999
• Status: Active Grant

• Current Assignee: Avery Tung, Lawrence J. Gottlieb, Michael F. Roizen
• Original Assignee: Avery Tung, Lawrence J. Gottlieb, Michael F. Roizen
• Inventors: Tung, Avery, Gottlieb, Lawrence J., Roizen, Michael F.
• Granted Patent: US 6,497,658 B2
• Time in Patent Office: Days
• US Class Current: 600/544
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/372 Analysis of electroencephalograms
• CPC Class Codes: A61B 5/386 Accessories or supplementary instruments therefor
• CPC Class Codes: A61B 5/4809 Sleep detection, i.e. determining whether a subject is asleep or not
• CPC Class Codes: A61M 2021/0022 by the tactile sense, e.g. vibrations
• CPC Class Codes: A61M 2021/0027 by the hearing sense
• CPC Class Codes: A61M 2021/0044 by the sight sense
• CPC Class Codes: A61M 21/02 for inducing sleep or relaxation, e.g. by direct nerve stimulation, hypnosis, analgesia for massage A61H; electrotherapy A61N, e.g. applying alternating or intermittent electric currents for producing anaesthesia A61N1/36021
• CPC Class Codes: A61M 2230/10 Electroencephalographic signals
• CPC Class Codes: A61M 2230/60 Muscle strain, i.e. measured on the user

Abstract

The present invention monitors a physiological process intrinsic to humans and which measures directly the approach of a sleep state. When sleep onset is detected, the subject is restored to a fully awake state by an alert mechanism. Sleep onset is determined by monitoring EEG and EMG signals of the subject with a bispectral index monitor and applying an analysis algorithm to the index values output by the monitor. As a person tires, the value of their bispectral index begins to drop and then oscillate back and forth between two discrete levels. This pattern is consistent among various subjects and indicates an early warning of impending sleep, before a dangerous loss of vigilance has occurred.

Claims

1. A method of detecting sleep onset and preventing sleep, the method comprising:

placing a plurality of contact leads on a subject that detect electroencephalogram (EEG) data and electromyelogram (EMG) data;

transmitting the EEG and EMG data to a processing device;

analyzing the EEG and EMG data for a sleep onset condition; and

alerting the subject when an sleep onset condition is detected.

2. An impeding sleep state alarm comprising:

a wakefulness monitor adapted to receive at least electroencephalogram (EEG) signals of a subject as an input and produce numerical index values as an output indicative of wakefulness of the subject;

a signal processor connected to receive the output indicative of wakefulness of the subject and programmed to analyze that output to detect onset of sleep; and

a feedback transducer connected to the signal processor so as to selectively produce an alarm signal to the subject in the event the signal processor detects onset of sleep.

3. The impending sleep state alarm of

claim 2

, wherein the output indicative of wakefulness of the subject comprises a bispectral index derived at least from EEG signals.

4. The impending sleep state alarm of

claim 2

, wherein the signal processor analyzes the output indicative of wakefulness based on the number of level transitions of the output per unit time.

5. The impending sleep state alarm of

claim 2

, wherein the signal processor analyzes the output indicative of wakefulness based on the length of time spent at or below the lower value of a predetermined transition range.

6. The impending sleep state alarm of

claim 2

, wherein the signal processor analyzes the output indicative of wakefulness based on attainment of a predetermined absolute threshold value.

7. The impending sleep state alarm of

claim 2

, wherein the feedback transducer provides an auditory stimulus to the subject.

8. The impending sleep state alarm of

claim 2

, wherein the feedback transducer provides a tactile stimulus to the subject.

9. The impending sleep state alarm of

claim 2

, wherein the feedback transducer provides a visual stimulus to the subject.

10. The impending sleep state alarm of

claim 2

, wherein the feedback transducer provides an electrical stimulus to the subject.

11. The impending sleep state alarm of

claim 2

, further comprising:

a transmitter connected to selectively produce an alarm signal to a remote location in the event the signal processor detects onset of sleep.

12. The impending sleep state alarm of

claim 11

, wherein the transmitter is selected from the group consisting of:

an RF transmitter, a computer, a GPS device, a network, and an infrared transmitter.

13. The impending sleep state alarm of

claim 2

, wherein the wakefulness monitor receives both EEG and electromyelogram (EMG) signals upon which the output numerical index values are based.

14. The impending sleep state alarm of

claim 2

, wherein the wakefulness monitor and the feedback transducer are co-located with the subject and the signal processor is located remotely therefrom.

15. The impending sleep state alarm of

claim 14

, wherein the signal processor comprises a general purpose computer implementing an algorithm for analysis of the output indicative of wakefulness of the subject based on the number of level transitions of the output per unit time.

16. The impending sleep state alarm of

claim 14

, wherein the signal processor comprises a general purpose computer implementing an algorithm for analysis of the output indicative of wakefulness of the subject based on the length of time spent at or below the lower value of a predetermined transition range.

17. The impending sleep state alarm of

claim 14

, wherein the signal processor comprises a general purpose computer implementing an algorithm for analysis of the output indicative of wakefulness of the subject based on attainment of a predetermined absolute threshold value.

18. The impending sleep state alarm of

claim 14

, wherein the signal processor is connected to receive the output indicative of wakefulness of the subject via a network.

19. The impending sleep state alarm of

claim 18

, wherein the network is a wireless network.

20. The impending sleep state alarm of

claim 14

, wherein the feedback transducer is connected to the signal processor via a network.

21. The impending sleep state alarm of

claim 20

, wherein the network is a wireless network.

22. An impeding sleep state alarm comprising:

a bispectral index monitor adapted to receive electroencephalogram (EEG) and electromyelogram (EMG) signals of a subject as an input and produce numerical index values as an output indicative of wakefulness of the subject;

a signal processor connected to receive the output indicative of wakefulness of the subject and programmed to analyze that output to detect onset of sleep; and

a feedback transducer connected to the signal processor so as to selectively produce an alarm signal to the subject in the event the signal processor detects onset of sleep;

wherein the bispectral index monitor and the feedback transducer are co-located with the subject and the signal processor is located remotely therefrom; and

wherein the signal processor is connected to receive the output indicative of wakefulness of the subject via a network, and the feedback transducer is connected to the signal processor via the network.

23. The impeding sleep state alarm of

claim 22

, wherein the signal processor analyzes the output indicative of wakefulness based on the number of oscillatory level transitions of the output per unit time.

24. The impeding sleep state alarm of

claim 22

, wherein the signal processor analyzes the output indicative of wakefulness based on the length of time spent at or below the lower value of a predetermined transition range.

25. The impeding sleep state alarm of

claim 22

, wherein the signal processor analyzes the output indicative of wakefulness based on attainment of a predetermined absolute threshold value.