The holiday season has arrived and with it comes gift shopping, parties and gatherings, large family dinners, and perhaps sleepless nights waiting with anxious anticipation for Christmas to arrive. This time of year also signals the arrival of a number of seasonal colds including influenza, RSV, and Coronaviruses. While you are busy sacrificing sleep to get all the shopping, work, and planning done before the holidays begin, you may be putting yourself at greater risk of getting sick. There has been growing evidence that sleep deprivation in the form of short sleep duration or poor sleep quality is associated with many conditions including: Type-2 diabetes, coronary artery disease, pneumonia, and even early death. One of the limitations of studies on the effect of sleep deprivation and disease is that they rely on the participant’s ability to recall how long they slept and how good the sleep was. As you may expect, people are not very good at recalling their sleep patterns with most people overestimating the amount of sleep they got and underestimating how restless it was. A new study published in the journal Sleep set out to more precisely measure the impact of poor sleep on a persons ability to fight off a cold.
The researchers recruited 164 otherwise health volunteers and asked them to wear a device on their wrist that would count how much time they spent asleep and how much time they spent awake. They tracked this data for 7 days and then put drops containing common cold virus into the participant’s noses. The subjects were quarantined for 5 days so that they could have their symptoms and infection tracked. The researchers hypothesized that the participants who slept for less or who had more restless sleep (measured by the watch) would be more likely to get a cold from the virus compared to the people who got longer sleep or more restful sleep. The results are summarized below:
- People who got 6-7 hours of sleep were not any more likely to get a full blown cold than the people who had more than 7 hours of sleep.
- People who got less than 6 hours of sleep per night were 2 to 4.5 times more likely to get a cold compared to people who got 7 or more house of sleep.
- People who had interrupted sleep were not more likely to get a cold compared to people who had uninterrupted sleep.
These results were independent of any other variables that would be considered risk factors for getting a cold. These include: gender, age, smoking status, stress level, physical activity, alcohol consumption, BMI, ethnicity, or season in which the experiment was performed. This indicates the immense importance of sleep in preventing colds. But how does sleep do this? Studies have shown that during the night the cells of your immune system move to special organs in the body that collect and house infected cells. Once there, your immune cells are able to effectively fight the infection. Less time asleep means these cells spend less time in these organs and less time fighting the infection. Sleep deprivation also dampens your immune systems danger signals and its ability to replenish the cells in its army.
It is assumed that the protective mechanism at play here is not specific to the common cold and should also be active in protecting you against other viral infections like influenza. So if you want to protect yourself this holiday season (or winter season) get some sleep and lots of it. Use it as an excuse to sleep in on the weekends or for having a nap after work. After all, your not being lazy, you’re staying healthy!