Anyone who has ever had a bad night's sleep knows about some of the most obvious signs of sleep deprivation — like being tired or irritable the next day. However, not as many people understand that there are long-term consequences to going without sleep — and these effects can be felt throughout the body.
According to Harvard Healthy Sleep, people who get less than six hours of sleep a night are more likely to have a higher body mass index (BMI) than those who sleep the recommended eight hours. During sleep, the body releases hormones that control appetite, energy metabolism, and glucose processing. One of these hormones is cortisol, the "stress hormone", which increases the body's levels of insulin -- and also makes it easier for the body to store fat. Another, according to Sleep Health Solutions, is ghrelin, which, at elevated levels, produces feelings of hunger: lack of sleep has been linked to higher ghrelin levels.
The U.K.'s National Health Service (NHS) also notes that the hormone leptin can play a role in this problem: leptin causes feelings of fullness; sleep deprivation is linked to decreased leptin in the body.
Increased Risk of Diabetes
Closely linked to the issue of weight gain is an increased risk for developing diabetes. Sleep Health Solutions notes that long-term sleep deprivation may increase the risk of this disease since insufficient sleep disrupts the body's method of processing glucose and poses a significant risk factor for diabetes. Harvard Health Sleep also cites one study that found that people who reduced their amount of sleep from eight hours a night to four-processed glucose more slowly than those who got enough sleep at night.
Increased Risk of Heart Disease
A person who is not getting enough sleep may also be at greater risk for developing heart problems according to Sleep Health Solutions. As is the case with weight gain and diabetes, the problem is hormonal: lack of sleep increases the levels of stress hormones in the body, raising blood pressure and heart rate and causing an inflammatory response in the heart itself. High blood pressure is linked to heart disease, heart attacks and stroke. Harvard Healthy Sleep reports that this is not only a long-term side effect; just one sleepless night can raise blood pressure the next day.
Insufficient sleep affects the mood. While a single night without sleep can cause irritability the next morning, chronic lack of sleep may result in long-term mood disorders, including anxiety and depression. Research indicates that cutting back on sleep can lead to feelings of sadness, anger, mental exhaustion, and decreased optimism and sociability, according to Harvard Healthy Sleep. The NHS reported a survey that found that most individuals suffering from anxiety or depression sleep for less than six hours a night. The connection between sleeplessness and mood disorders may be due to low levels of the hormone melatonin, reports Sleep Health Solutions. This hormone helps to regulate both sleep cycles and mood and depressed patients often present with below normal melatonin levels.
Individuals who do not get adequate sleep are more likely to use alcohol. Alcohol acts as a mild sedative, and for that reason, many people who suffer from restlessness use it as a sleep aid. However, while alcohol initially causes sleepiness, alcohol can actually interfere with a good night's sleep: after a few hours, the soporific effect wears off and it causes the person to begin waking up and also have difficulty getting back to sleep.
In short, while daytime drowsiness and irritability can be frustrating to deal with, it is actually the long-term effects — including weight gain, heart problems, and diabetes — that can disrupt the balance of various hormones in the body and seriously impact health.