Help turning spectral analysis output into time variables

I'm new to Matlab and am using it to analyse sleep EEG data from a rodent. Each file contains 24hr sleep recordind with each 4sec scored to different stages of sleep.

I've analysed the data to give me frequency plots using spectral analysis and using FFT on the data but don't know how to convert this into time to get things like total sleep time, time spent in each stage of sleep and percentages.

Please if anyone could provide some help or have got a script/toolbox for this type of analysis that would save my masters.

Answer 1

[Star Strider]

You do not provide enough information as to the data you have and the information you want from your data.

Consider using the spectrogram function if you want the frequency content of the rodent EEG as a function of time, and have not already done so. (The term ‘spectral analysis’ can mean different things.)

Alternatatively, if I remember correctly, different sleep stages are related to the EEG frequency components during those stages. You can determine the frequency components with respect to time using the bandpass function (R2018a and later), or creating your own bandpass filters from command-line functions. Set the filters up in parallel, so that they produce different results from the same time-domain data. Then determine the power (amplitude.^2) in each output, and classify them using that information. This is somewhat more difficult, however it may give you more detailed information.

The fft and spectrogram give you a significant amount of information, however those cannot readily be useful if you want detailed information with respect to frequency content as a function of time. The filter approach can do that.