Sleep assessment messages missing timestamp

Hi,

I decode FIT files in XCODE using SwiftFIT library and I cannot figure out how to tie the Sleep Assessment messages (FITSleepAssessmentMesg)

to a timestamp (or to a particular sleep or date) as this type of message does not contain its timestamp unlike other types which do have getTimestamp() eg FITHrvStatusSummaryMesgs.

Any advice how to solve it?

Thanks a lot!

Jaroslav