If underlying chronic stress from too much time commuting, social conflicts, or endlessly tough homework assignments elevates stress hormones like cortisol above normal levels, we become more alert at night when we’d otherwise become drowsy, or we wake up after one or two NREM and REM cycles.60 Then as we become chronically sleep deprived, we produce more cortisol, especially at night, which can then inhibit sleep, keeping the problem going and promoting insomnia.
