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What Causes What
MECHANISM0 NULL

Sleep duration and regularity → Depression

A rise in Sleep duration and regularity does not identify a change in Depression.

In 126 adults with insomnia and major depression, adding internet CBT for insomnia to CBT for depression improved the insomnia score but not the depression score versus depression treatment plus a placebo sleep module.

Randomized trial · Moderate · N=126

Supported by an experiment or a tightly identified design. Read the caveats.

Mechanism

Blom, Forsell, Hellberg and colleagues assigned 126 adults with physician-diagnosed insomnia and major depression to twelve weeks of therapist-guided internet CBT in Stockholm psychiatry (NCT01663844). One arm mixed CBT for insomnia with CBT for depression. The other mixed CBT for depression with a quasi-desensitization placebo for sleep. Sleep restriction and stimulus control were the insomnia pieces. Behavioral activation was the depression piece. The combined arm beat control on the Insomnia Severity Index (group by time p=0.007). It did not beat control on the Montgomery-Åsberg self-rating (p=0.11). Observed means went from 24.1 to 18.6 versus 24.0 to 17.4. The between-group d at post was -0.16. Carney, Edinger, Kuchibhatla and colleagues assigned 107 adults with SCID major depression and insomnia to four biweekly sessions plus a daily pill: CBT-I plus escitalopram, CBT-I plus placebo, or escitalopram plus sleep-hygiene talk. Hamilton scores fell in every arm and the arms did not differ. The CBT-I plus placebo arm had no depression treatment and still fell, 25.52 to 14.67. Remission below 8 was 39, 39, and 41 percent. The authors name time out of bed, less rumination in bed, morning light, and leftover REM as candidate paths. Those paths did not produce an extra depression drop once depression was already being treated.

Caveats

Blom's control already received a full CBT for depression. The test is the insomnia increment, not CBT-I versus nothing. Removing the sleep item from MADRS-S moved the interaction toward the control (p=0.054). Combined therapists spent more minutes, 154 versus 111. Stockholm, internet, 2013 to 2017. Inclusion allowed minor depression if MADRS-S was above 19. MADRS-S remission was 22 percent versus 34 percent at post, not a significant difference. Carney aimed for 201 and stopped at 107. The CBT-I plus placebo arm still took a pill. There is no no-treatment control. Four sessions, novice graduate therapists. Follow-up only for people who remitted, so durability is unknown. Hamilton includes sleep items; dropping them did not change the group test. The papers name 126 and 107 people. This page is CBT-I for insomnia, not a one-week inpatient restriction protocol. This is a journal entry, not medical advice and it is not a reason to start or skip a therapy.

Effect

qualitative. Blom 2024 n=126: MADRS-S group by time p=0.11, between d=-0.16. Carney 2017 n=107: HAMD-17 groups ns. CBT-I plus placebo matched AD. Archive n empty.

Nodes

Lifestyle & environmentSleep duration and regularityPsychology & behaviorDepression

Named confounders

Cite this page

What Causes What. “Sleep duration and regularity → Depression.” https://whatcauseswhat.org/edges/e-sleep-depression (atlas updated 2026-09-02).

https://whatcauseswhat.org/edges/e-sleep-depression

Papers