The amount of sleep each person needs varies between individuals but the average adult needs between 7-8 hours a night, the average teen needs 9-10 hours a night, and the average child needs at least 10 hours of sleep a day. However, nearly 30% of adults get less than 6 hours of sleep per day and only 31% of high school students get more than 8 hours of sleep a day. This chronic sleep deprivation can lead to difficulties with concentration, memory, performance at school or work, and driving. In 2009, 37.9% of people in the US reported falling asleep at least once during the day and 4.7% reported nodding off or falling asleep behind the wheel. In addition to the obvious physical harm that comes from driving while tired, chronic sleep deprivation can also lead to depression, type-2 diabetes, obesity, increased blood pressure, and even seizures. There is some evidence that sleep deprivation increases your risk of catching a cold and this is likely due to a suppressed immune system. A research team from Washington set out to determine whether chronic sleep deprivation affected the activity of the immune system. They hypothesized that lack of sleep would kick the immune system into overdrive and that this could explain the risk for diabetes and obesity in people who are sleep deprived. However, their results showed that sleep deprivation actually caused a profound decline in immune function.
To perform this study, the researchers recruited pairs of identical twins who had at least 1-hour difference in their sleeping patterns. This meant that for the study, one twin was chronically sleep deprived and one was not. The researchers used twins so they could rule out the effect of genetics on the results. The sleep patterns were measured for 2 weeks in order to confirm the extent of the participants sleep depravation. On the final day blood was taken and gene expression analyzed to look for differences between the sleep deprived and non-sleep deprived twin. The researchers found suppression in a distinct pattern of genes that were associated with immune function in the people who were sleep deprived. These genes were involved in activation, control, and recruitment of the immune system as well as in wound healing processes in the body. Key pathways that were changed were:
- Cytokine-receptor interactions (Used for communication between immune cells)
- Natural Killer Cell signalling (key for fighting off viral infections)
- B-cell receptor signalling (key for making antibodies)
- GM-CSF pathway (important for innate immune system)
These results suggest that sleep deprivation suppresses normal immune system function and may make people more susceptible to viral or bacterial infections. It is not known how or why the immune system becomes suppressed with chronic sleep loss but it is likely tied to the circadian rhythm or your internal clock. It is important to maintain a normal sleep schedule and ensure adequate sleep time in order to prevent chronic diseases and apparently, to prevent colds.
Photo Credit: Flickr Aaron Edwards