Interrupted sleep is worse than a short sleep and its effects are cumulative

A short amount of sleep can be more beneficial than a longer period of interrupted sleep, according to a study by researchers at Johns Hopkins University School of Medicine. Specifically, the research found that waking up several times during the night had a negative effect on a person’s mood.

The study, which was carried out on healthy subjects with generally normal sleep patterns and published in the journal Sleep, observed 62 healthy men and women who were subjected to three sleep conditions in a clinical research suite: three consecutive nights of either forced awakenings, delayed bedtimes or uninterrupted sleep.

The researchers found that after one night, participants who were woken up eight times and those with delayed bedtimes displayed similar signs of negative mood, as measured by a standard questionnaire.

After the second night significant differences emerged between the test groups. Those whose sleep was interrupted experienced a 31 per cent reduction in positive mood, compared with just 12 per cent for those who were kept awake late.

Patrick Finan, the study’s lead author, says: ‘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.’

Finan says the results are likely to apply to those who suffer from insomnia, and people who are commonly woken up through the night, such as new parents and on-call health care workers.

The researchers found that interrupted sleep not only reduced energy levels, but also feelings of sympathy and friendliness. Finan says the study also suggests that the effects of interrupted sleep on positive mood can be cumulative. ‘You can imagine the hard time people with chronic sleep disorders have after repeatedly not reaching deep sleep. Further studies are needed to learn more about sleep stages in people with insomnia and the role played by a night of recovering sleep.’