How did you sleep last night? Many people answer “not great” when asked how they slept last night. In the U.S., around a third of people sleep less than seven hours a night, which is the minimum recommended. We are all familiar with the unpleasant side effects. It can make it difficult to do everyday tasks. Research by Eti Ben Simon ,, a postdoctoral fellow at University of California, Berkeley, shows that sleeplessness can also affect parts of the brain that impact our social lives and ability to relate to others. People who sleep less are less likely help others. Ben Simon spoke to Daisy Yuhas, Mind Matters editor, to discuss the social consequences of poor sleep and how good sleep can be used to improve well-being.
[ An edited transcript of the interview is . ]
In past research, you and your colleagues have found that lack of sleep contributes to anxiety and difficulty managing emotions. You’ve also discovered that poor sleep can affect social interactions, regardless how mood-related. How does this work?
People are less interested in social interaction if they’re not sleeping enough. We designed a task in which an experimenter and a participant would face eachother and walk towards each other. We would measure the distance and let the participant decide when someone is too close. People prefer to be further away when they are sleep-deprived.
Mood might play a role in the social consequences associated with sleep loss. However, it’s not the only factor. In studies of social behavior, we have found that social withdrawal is more than a result of mood.
We’ve also found that sleep deprivation reduces activity in what’s known as the theory of mind network in the brain. These areas help us think about others–what they might like, what they look like, and how they differ from us.
How might these brain changes relate to our thinking?
In a recent study, participants were asked to think about other people while their brain activity was being monitored in an fMRI scanner. They were then asked to answer a questionnaire about their willingness to help others. We asked them about their daily acts of kindness, such as helping someone carry their groceries, keeping the elevator door open, and other things like that.
We found that sleep-deprived people were significantly less likely to want to help others, and that correlated one to one with the impairment in their theory of mind network. The greater the impairment, the less they want to help others. It didn’t matter if they were helping a friend or a family member.
Total sleep deprivation is pretty extreme. What if people got at least some sleep?
In a second study, the same questionnaire was used, but this time we tracked people’s natural sleeping patterns over four nights and seven days. We didn’t find any association with how much people slept in hours, but we found that the quality of their sleep–how many times they woke up during the night, whether they had a restful sleep or their sleep was fragmented–determined whether they were likely to want to help others or not.
People who aren’t well rested often say they don’t want to help others. Have you ever noticed a difference in helping behaviors when sleep deprivation is present?
Yes. A third study was done. We looked at a database of charitable donations. We compared the week of [the shift to] daylight savings time, which is when people lose an hour of sleep, to other weeks of the year. In 15 years’ worth of data, we kept seeing that on that week, the amount people donate is reduced by about 10 percent.
In Arizona and Hawaii, which don’t have daylight saving, we don’t see this effect. We also looked at the effect of switching to standard time, which is when people “fall back,” but didn’t see one. These data combined show that lack of sleep may affect altruistic sentiment in the U.S .
Other scientists are also looking at similar questions. Just a few months ago a colleague of mine published a study that found doctors prescribe fewer painkillers during a night shift than a day shift, and that was accompanied by reduced empathy for their patients.
You’ve also found that one person’s sleeplessness affects everyone around them. How is that possible?
In general, it’s amazing how quickly we can pick up on something that’s wrong with someone we’re interacting. One study found that a short video clip of a person talking was enough to alert others to the fact that they don’t want to interact or communicate with someone who is sleep-deprived.
Loneliness can be caused by sleep deprivation. We’ve found that people who have had contact with people who are sleep deprived report feeling lonely. I like to say that it helps answer the Beatles’ question: “All those lonely people, where are they all from?” It all began with sleep loss.
I worry about a negative feedback loop that leads to loneliness. If you are chronically sleep-deprived, the feeling of not connecting with others can only get worse. You may feel more isolated and less interested in interfacing with others. We’ve also seen that others are less interested than you in interfacing with them.
Could that in turn contribute to the connection between sleep and conditions such as anxiety or depression?
There is a close connection between mental health and sleep deprivation. People who have disturbed sleep patterns are more likely to suffer from anxiety and depression later in life. For example, anxiety is characterized by disturbed sleep. When you are stressed out, your sleep becomes impaired. You need more sleep to feel calmer.
We’re such social beings. Why would our sleepy brain shut off the network that connects us with others?
The brain and body need to sleep so much that they begin to let go of everything they don’t need immediately after sleep is lost. The only times you see animals sleeping is when they are migrating, having a baby, or starving. Being sleep-deprived is a stress signal, which makes us want to eat as much as possible and to be more alert to dangers. We can’t do more than that.
The more time you spend awake the more you will need to be focused on sleep. Everything else is just a background noise.
On the flip side, does this mean that we should get more sleep and do more exercise to improve our mental health?
Exactly. It’s possible to intervene in social and emotional affective disorders through sleep.
Sleep, before diet and exercise, is the bedrock. Good sleep is crucial for how our bodies metabolize food and how our muscles react to it.
It’s not always easy for people to get good sleep. It is possible to shift moods, anxiety, and even kindness if we make a priority of it.
Are your interests in psychology, neuroscience, or cognitive science? Have you ever read a peer-reviewed paper you would like to write about in Mind Matters? Please send suggestions to Scientific American‘s Mind Matters editor Daisy Yuhas at firstname.lastname@example.org.