If you’ve ever spent a night tossing and turning, you already know how you’ll feel the next day — tired, cranky, and out of sorts. But missing out on the recommended 7 to 9 hours of shut-eye nightly does more than make you feel groggy and grumpy. The long-term effects of sleep deprivation are real. It drains your mental abilities and puts your physical health at real risk. Science has linked poor slumber with all kinds of health problems, from weight gain to a weakened immune system.