Most of the time, if you’re not getting enough REM sleep, you’re going to feel it in a big way. Signs of lack of deep sleep include lethargy, dozing off, trouble waking in the morning, brain fog, and irritability. Another clue you’re not getting enough REM is if you never dream. It’s common to not remember most of your dreams, but if you never remember a single one or wake up feeling like you dreamt, it could be a sign you’re not cycling into REM. Only sleep monitoring technology such as sleep trackers or sleep EEG can tell for sure, so if you’re afraid you’re not sleeping deeply enough, speak with your doctor about a sleep study.