Unfortunately, sleep deprivation can become the norm for some people, plus a vicious cycle is created when increased daytime stress makes sleep elusive at night, while lack of quality sleep contributes to stress during the day. Over time, it can seriously damage physical and mental health. Sleep is especially important for the developing brain. Late nights and erratic bedtime routines blunt children’s brainpower, according to last year’s University College London study of more than 11,000 seven-year-olds.