The scientists found that after an insufficient night of sleep, people have a reduced capacity for remaining positive when faced with emotionally challenging events. They are also less able to enjoy positive experiences.
The lead author of the study, health psychologist Nancy Sin of UBC, describes how this results in more stressful days for people who do not get enough sleep:
“When people experience something positive, such as getting a hug or spending time in nature, they typically feel happier that day. But we found that when a person sleeps less than their usual amount, they don’t have as much of a boost in positive emotions from their positive events.”
Stress is associated with a range of harmful effects, compounding the damage done by sleep deficits.
The study appears in the journal Health Psychology.
“The recommended guideline for a good night’s sleep is at least seven hours, yet one in three adults don’t meet this standard,” says Sin.
To explore the effects of insufficient sleep, Sin and her colleagues analyzed an existing data set of 1,982 United States residents, 57% of whom were female. The participants gave their sociodemographic details and existing chronic conditions to the researchers at the start of the study.
The individuals kept daily diaries. For eight consecutive days, they were interviewed daily via phone calls, during which participants reported the number of hours they had slept the previous night.
Each person also described the events of their day. They recalled problems they had encountered: interpersonal tensions, arguments, feeling of discrimination, and stresses with their work associates and family. They also recalled the good things that happened. In addition, participants reported their emotional responses from that day, both positive and negative.
The pattern that emerged was a lessened ability to remain or feel positive when participants had less sleep. When experiencing stress, they found it harder to maintain emotional equilibrium. And when good things happened, feelings of joy or happiness were muted.
Such days may be more than unpleasant — earlier research, including Sin’s own, has found links between an inability to retain feelings of positivity and inflammation, as well as death.
“A large body of research shows that inadequate sleep increases the risk of mental disorders, chronic health conditions, and premature death. My study adds to this evidence by showing that even minor night-to-night fluctuations in sleep duration can have consequences in how people respond to events in their daily lives.”
– Nancy Sin, UBC
The researchers found no evidence that not getting enough sleep increased participants’ negative emotions the following day.
Previous research has found that individuals with chronic health conditions, including diabetes, cancer, and heart disease, tend to be more emotionally reactive when confronted with stressful events. Considering that getting more sleep could help to prevent this, Sin says she was interested to learn “whether adults with chronic health conditions might gain an even larger benefit from sleep than healthy adults.”
The study’s finding suggests this might be the case, she says.
“For those with chronic health conditions, we found that longer sleep — compared to one’s usual sleep duration — led to better responses to positive experiences on the following day.”
Sin hopes that studies such as hers will convince people to prioritize getting enough sleep as a way to stay healthy and have better days.
