Acute to chronic insomnia transition warns of depression risk

By Lucy Piper, Senior medwireNews Reporter

In patients with acute insomnia, long periods of light sleep may be the key driver to chronic insomnia and depression, research suggests.

The study showed that patients with acute insomnia who developed chronic insomnia had significantly reduced N3 sleep at baseline, compared with normal sleepers and other patients with acute insomnia.

Patients with chronic insomnia also showed shorter rapid eye movement (REM) latencies than patients who remitted and were more likely to develop first-onset depression during 3 months of follow-up, at a rate of 9.26%, compared with 1.85% for patients who remitted, and 1.85% for normal sleepers.

Lead researcher Jason Ellis (Northumbria University, Newcastle-upon-Tyne, UK) and colleagues note that these sleep deficits have also previously been observed before and during episodes of depression.

They therefore speculate that acute insomnia may represent a risk factor for future depression. Acute insomnia in combination with an unknown factor may result in reduced REM latency and decreased N3 sleep in individuals who go on to develop chronic insomnia, which in combination increases the risk for first-onset depression, they explain.

The study, published in Sleep, involved 33 individuals with acute insomnia (meeting DSM-5 criteria for insomnia for between 3 days and 3 months) and 21 normal sleepers, none of whom had a history of a sleep disorder or psychiatric illness.

At baseline, individuals with acute insomnia had significantly more stress and higher anxiety and depression scores, as measured on the Social Readjustment Rating Scale, the Perceived Stress Scale, and The Hospital Anxiety and Depression Scale, respectively, than normal sleepers.

The two groups did not differ significantly in terms of polysomnography sleep continuity parameters, but they did differ with regard to sleep architecture, with people with acute insomnia showing a greater percentage of N2 sleep (54.08 vs 47.57%) and reduced percentage of N3 sleep (9.41 vs 19.99%).

Among the patients with acute insomnia, 42% still had insomnia 3 months later and were classified as having chronic insomnia, while the remaining 58% had remitted.

Stress and anxiety severity had no bearing on whether or not patients transitioned to chronic insomnia or remitted. The only difference between these two groups was that patients with chronic insomnia had reduced REM latency (66.32 vs 97.08 minutes) and reduced N3 sleep (6.51 vs 11.55%).

“The present findings suggest that the ‘sleep architecture stigmata’ of depression may actually develop over the course transitioning from acute to chronic insomnia,” the researchers conclude.

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