Johns Hopkins Medicine researchers identified a correlation between bad moods and interrupted sleep, finding that people who napped for a short period of time and woke up on their own were happier than those who were allowed to sleep over a longer duration, but were woke up repeatedly in the midst of their slumber.
Sixty-two men and women, all absent of any sleep-related health issues such as insomnia, partook in the sleep experiment, in which three experimental conditions existed. Researchers subjected the participants to three nights of either forced awakenings, delayed bedtimes or undisturbed sleep at an inpatient clinical research suite.
According to Today, the participants subjected to forced awakenings were also forced to stay awake for 20 minutes, once every hour; a sleep pattern that a new parent might have to deal with.
Researchers surveyed the participants to find out their positive and negative emotions, rating how strongly they felt joy, friendliness, excitement, cheerfulness, anger and other emotions.
EurekAlert! reports that subjects who experienced eight forced awakenings on the first night showed similar emotions to those with delayed bedtimes, as indicated by participants in the survey.
On the second night, however, noticeable differences became evident, as the forced awakening group had a 31 percent reduction in positive mood compared to the first day. Those forced to stay up late experienced a smaller decline of just 12 percent.
Surprisingly, the researchers were unable to identify any oscillations in negative emotions among any of the groups examined over the duration of the study. However, since participants reported having a reduction of positive emotions such as friendliness and sympathy, researchers came to the conclusion that interrupted sleep has an especially detrimental effect on positive mood.
According to the study’s lead author Patrick Finan, those who experience disruptions in their sleep overnight are unable to progress through the normal sleep cycles that lead to the feeling of restoration the next day.
When your sleep is disrupted throughout the night, you don’t have the opportunity to progress through the sleep stages to get the amount of slow-wave sleep that is key to the feeling of restoration.
Those who were forced to wake up during their resting period were prevented from entering any period of “deep , slow-wave sleep”, leaving people drained of energy and unhappy the next day.
Finan noted that though the participants of the study did not have insomnia, the results of the study will still likely apply to those who have the sleeping disorder.
Peter Franzen, a sleep expert not associated with the study from the University of Pittsburgh School of Medicine, told Today that he found the study unique. The numerous studies of sleep in the past focused on the impact of sleep restriction, rather than multiple awakenings, according to Franzen. Multiple awakenings “is probably [a] more valid way of looking at insomnia”, as it answers some questions about the effects of fragmented sleep, he said.
Finan warns that effects of fragmented sleep may be cumulative, as the findings suggest the negative emotional impact only gets worse on subsequent days if the sleeping pattern persists.
