Welcome to the medhelp neurology forum and thanks for this query. I agree with you that irregular sleep patterns are linked with memory loss. A sleep deprived person cannot focus attention optimally therefore cannot learn efficiently. Secondly sleep itself has a role in consolidation of memory which is essential for learning new information. For proper memory function, acquisition, consolidation and recall. Though acquisition and recall occur during wakefulness, memory consolidation occurs during sleep by strengthening of neural connections that form our memories. EEG can identify the sleep cycle which is a repetition of 4 to 6 cycles of NREM non rapid eye movement and REM rapid eye movement sleep starting with NREM sleep. With lack of sleep there is reduction In the time spent in the deepest stages of NREM( stages 3 and 4). Any loss in this activity is replaced by stage 2 NREM sleep. The EEG can read these phases of sleep and can give clue to a sleep deficit.
I hope this helps. Please feel free to contact me for any clarifications.
Thanq very much for your response and clarification regarding my question .