disrupted sleep, insomnia
More sleep isn't always better for your mood.

In fact, more sleep that's disrupted reduces positive moods more than less sleep that's uninterrupted, a new study finds.

Uninterrupted sleep is particularly beneficial for the positive emotions of friendliness and sympathy for others.

Dr Patrick Finan, who led the study, said:
"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."
The study compared three groups who came into a sleep lab for three nights:
  • One group were forcibly awakened throughout the night.
  • Another group had their bedtime delayed.
  • A final group were left to sleep normally.
People were asked about their positive and negative moods during the day.

After two nights, the different groups started to diverge.

People whose sleep was interrupted had 31% less positive mood during the day.

Those who had their sleep delayed experienced 12% less positive mood.

There was little difference in negative moods.

Naturally those in the study who'd slept solidly also felt more energetic.

So it seems that interrupted sleep mainly dampens the feelings of positive emotions rather than increasing negative emotions.

Frequent awakenings during the night is one of the symptoms of insomnia.

Dr Finan said:
"Many individuals with insomnia achieve sleep in fits and starts throughout the night, and they don't have the experience of restorative sleep."
The study was published in the journal Sleep.