Dear Sleep,

I love you. I really do. I may have fought you as a kid, refused you as a teen. But now I miss you – because you are excellent – and nothing feels the same without you. Now I know why …

New research has found that eight hours of interrupted sleep can be as physically detrimental as sleeping for only four.

Parents, professionals on call, shift workers and students would know the feeling. As would anyone with a weak bladder or anyone in shouting distance of a barking dog. So too would anybody who has been tossed and turned by the hand of some sort of life stress.

Night waking is a pervasive phenomenon for many people.

In a study published in the journal Sleep Medicine, researchers have demonstrated that interrupted sleep leads to diminished cognitive capacity, shortened attention span and a bad mood.

Interruptions of five to ten minutes are enough to disrupt the natural sleep rhythm.

What They Did

Participants in the study were university student volunteers. Their sleep patterns were monitored using wristwatch-like devices that monitored sleep and awake.

On the first night of the study, students slept for eight hours.

Then, on a subsequent night, they were woken up four times by phone calls and instructed to complete a short computer task of about 10-15 minutes duration, after which they could go back to sleep.

The following morning, students completed a set of computer tasks that measured alertness and attention. They were also asked to self-report their mood.

What They Found

One night of interruptions was enough to compromise cognitive function and mood. Attention and alertness were diminished and people reported feeling fatigued, depressed, confused and lethargic. In fact, the effects were as drastic as if they had only slept for four hours.

No effects were found on anger and anxiety, suggesting that these features of mood are less sensitive to fragmented sleep.

In real life, interrupted sleep can continue for many nights on end, sometimes for months or even years. The effects of disrupted sleep accumulate over time.

Researcher Professor Sadeh explained, ‘Our study shows the impact of only one disrupted night. But we know that these effects accumulate and therefore the functional price new parents – who awaken three to ten times a night for months on end – pay for common infant sleep disturbance is enormous. Besides the physical effects of interrupted sleep, parents often develop feelings of anger toward their infants and then feel guilty about these negative feelings.’

Importantly, the findings lend support to previous research that has found an association between child sleep disruptions and maternal fatigue, stress and depressive symptoms.

Sleeping is one of the best things you can do for your brain. It’s cleansing, restorative, keeps you functioning and playing nicely. Anything you can do to keep your zzz’s unbroken will pay you dividends. And if anybody comes up with a way to achieve that with kids, barking dogs, a Goldilocks-ish too hot/too cold relationship with the doona and a completely hopeless love affair with late nights, would you pleeeease let me know.