Skips recording every day for specific times


I have a dome camera for 2 years and it was working fine recording continuously on the 128 GM sd card with about 7 days of recording in SD and then it overwrites. In last few weeks my camera has started showing GAPS in the recording. For instance It will record for an hour and there will be 5 -10 min or no recording and so on. Whats more weird is that every day from around 1:00 am to about 7:00 AM it wont record anything. Its not an SD card issue as i have changed the card an same issue. I have also reset the camera but no use. Can someone help?