Try having kids, shift work, or just be older than 40. Your sleep naturally declines as you age, and though sleep time declines, the more detrimental factor is

Try having kids, shift work, or just be older than 40. Your sleep naturally declines as you age, and though sleep time declines, the more detrimental factor is the lack of slow-wave delta activity. Your brain literally gets worse at the restorative function that is vital to sleep.