Getting too few hours of sleep a night can affect your mood, energy level, and, according to a study presented at the American College of Cardiology conference earlier this year, it can also raise your risk of developing high blood pressure, diabetes, obesity and depression. In the study, partcipants had their blood pressure monitored throughout the 16-day trial. The results showed that the study participants who got only four hours of sleep a night had an average nighttime blood pressure of 115/64 mmHg, compared to 105/57 mmHg for the subjects who received nine hours of sleep each night. Nighttime heart rates also increased among the group who slept only four hours each night. In this study, the participants were healthy adults between the ages of 18 and 36. But researchers suggest that for older people who already have high blood pressure, this nighttime surge should be a real concern. If you have hypertension, even if its generally well-controlled with medications and lifestyle, you should take note of how many hours of sleep you get each night. If you consistently get less than seven hours of sleep per night, you should tell your doctor. This is true even if you dont have high blood pressure. There may be causes, such as obstructive sleep apnea, that are interfering with your sleep. It may be that you simply need to adjust your bedtime routine, go to sleep earlier, avoid caffeine, or exercise more to help you sleep better. Knowing that poor sleep raises your blood pressure at night should also prompt a conversation with your doctor to determine whether you should adjust the time you take your blood pressure-lowering medications.