Links between insomnia and depression: can treating one problem also improve the other?

In people who suffer from both depression and insomnia, cognitive behavioral therapy for insomnia was as effective as CBT for depression (CBT-D) at decreasing the severity of depressive symptoms, and more effective than CBT-D at improving insomnia. These findings come from a small but randomized Swedish study involving 43 patients and follow-up data at three years. CBT was delivered over the internet.

In people with co-occuring depression and insomnia, CBT for insomnia was as effective as CBT for depression at decreasing depression severity

In their recently published paper (reference below) Kerstin Blom and colleagues from the Karolinska Institute, Stockholm, conclude that patients with co-occurring depression and insomnia should be offered CBT for insomnia as well as receiving medication or psychological treatment for depression.

Internet-based CBT

Tiina Paunio (University of Helsinki, Finland) and Eus van Someren (Netherlands Institute for Neuroscience, Amsterdam), who moderated the session, agreed that there is great promise in internet-based CBT for insomnia. And CBT is probably more consistently effective than drug treatment of the insomnia. Antidepressants differ in their direct effects on sleep, though by alleviating depression sleep can be improved.

The first step in dealing with insomnia is to record the problem systematically using a sleep diary, and then try to tackle any obvious contributing factors such as substance abuse. If necessary, polysomnography can chart the different levels of sleep and the way they are distributed through the night. Patterns are highly variable between people, but tend to be similar in identical twins – suggesting a degree of heritability.

Insomnia and depression may share some underlying genetic variability and have overlapping neurobiological characteristics

Shared social factors, genes and neurobiology

In terms of the potential overlap in etiology, childhood adversity is a risk factor for both insomnia and depression. For insomnia, adverse childhood experience more than doubles the risk of fragmented REM sleep. It seems that normal sleep plays a role in “dissolving” distress, Eus van Someren said. But if REM is fragmented, stress may accumulate, leading to the hyper-aroused state that characterizes insomnia

Preliminary studies suggest there may be 20-50% shared heritability in insomnia and depression

There is growing evidence of a heritable element in insomnia, and work in progress aims to identify the specific genes that increase risk. More research is needed but studies from Finland suggest 20-50% of heritability is shared by insomnia and depression.

This would be reflected in shared neurobiology. Pathways involved in stress regulation, inflammatory processes and neural plasticity may contribute both to depression and to insomnia.

Insomnia is one of the symptoms that bother depressed patients the most; and it can persist when patients feel better in other respects.

Between 4% and 10% of the general population have a sleep complaint – defined as sleep that is disturbed enough to have adverse daytime consequences at least three times a week for three months or more.