I just got a HR monitor from 60 Beat Blue that syncs with iPhone 4S or greater. Quickly found a cool free app: wahoo fitness that will export data from all sorts of devices including GPS coords and the above HR monitor to email or your dropbox folder via .csv format. Threw the results into excel and this is my heart rate over 8 hours of sleep last night. Some looming signs of sleep apnea maybe.. next to perform a fourier transform (excel is not so good at that with so many datapoints (27K)), and then actual excersize.