Anyone who’s ever pulled an all-nighter to meet a deadline or study for a test knows the day-after results aren’t pretty: The body feels sluggish, the mind fogged or frenetic. Recent research shows that a chronic lack of sleep is far more damaging than previously assumed by many experts. Sleep deficits as small as an hour a night can increase the risk of a wide range of conditions. Why? Because when we don’t get enough sleep, our immune systems go into overdrive, which causes systemic inflammation and turns on dangerous genetic switches.

Everyone’s immune system is unique, so how sleep deprivation affects you might be different from how it affects another person. Here are just some of the ways chronic skimping on sleep can affect your health:

• Neuropsychiatric disorders, impaired alertness and cognition, and headaches
• Vision problems, including blurred vision, floppy eyelid syndrome, glaucoma, even temporary blindness
• High blood pressure
• Increased levels of cortisol, a hormone associated with stress
• Cancer
• Difficulty with sexual functioning
• Increased food cravings and hunger
• Insulin resistance, type 2 diabetes
• Hearing loss
• Muscle weakness and decreased athletic performance
• Heart disease
• Skin problems and rashes, including eczema
• Hair loss
• Disrupted metabolism, weight gain and obesity