Apparatus, method and system of measuring sleep state

A method of measuring a sleep state, comprising:

• obtaining a user's autonomic nerve index by measuring a user and obtaining a temporal change of the autonomic nerve index according to a time lapse;
• determining a parameter of a cosine or sine function which has the minimum error with respect to the change of the autonomic nerve index to obtain the cosine or sine function using the parameter as a time function showing a user's sleeping cycle;
• and
• calculating a sleep periodicity index based on a difference between the temporal change of the autonomic nerve index and a change of the time function showing a user's sleeping cycle, wherein the sleep periodicity index indicates whether the user is sleeping or not according to a periodic sleeping cycle as an index.

A system of measuring a sleep state comprising:

• a sleep state measuring apparatus that performs a measurement of a user;
• and
• an information processing apparatus that communicates with the sleep state measuring apparatus,
• wherein the sleep state measuring apparatus includes
• an autonomic nerve index obtaining unit that obtains a user's autonomic nerve index by measuring the user and obtains a temporal change of the autonomic nerve index according to a time lapse;
• and
• a data transmitting unit that transmits the autonomic nerve index, and
• the information processing apparatus includes
• a data receiving unit that receives the autonomic nerve index;
• and
• a sleep periodicity index calculating unit that calculates a sleep periodicity index based on a difference between the temporal change of the autonomic nerve index and a change of a time function showing a user's sleeping cycle, wherein the sleep periodicity index indicates whether the user is sleeping or not according to a periodic sleeping cycle as an index,
• wherein the sleep periodicity index calculating unit includes a sleeping cycle obtaining unit that determines a parameter of a cosine or sine function which has the minimum error with respect to the change of the autonomic nerve index and obtains the cosine or sine function using the parameter as the time function showing the user's sleeping cycle.