Significant REM Sleep Differences Seen in Patients With MDD and Insomnia

People with major depressive disorder (MDD) enter rapid-eye movement (REM) sleep sooner and remain in that sleep stage longer than those with insomnia. By contrast, patients with insomnia sleep less, wake up more throughout the night, and spend more time in non-REM stage 3 (N3) sleep, according to a recent meta-analysis published in Sleep Medicine Reviews.

MDD and insomnia are both prevalent mental disorders that often co-occur with one another. While prior research has suggested the 2 conditions have a bidirectional relationship, the dynamics and mechanisms underlying the association are not completely understood. Insomnia often occurs before MDD onset and research has suggested a correlation between this onset with both emotional dysregulation and emotional processing. Because REM sleep fragmentation may obstruct emotional regulation, further research is needed to determine the effect of sleep fragmentation on both insomnia and MDD.

To better understand the connection between REM sleep patterns in patients with either insomnia or MDD compared with healthy controls, investigators conducted a network meta-analysis of polysomnography (PSG) studies published between 2008 and January 2023. Of the 103 studies included, 17 focused on MDD and 86 focused on insomnia. Across all included studies, there were 636 patients with MDD compared with 491 patients in the healthy control group and 3661 patients with insomnia compared with 2792 patients in the healthy control group.

Compared to the control group, patients with MDD had increased REM density (FE model=2.03 [95% confidence interval (CI), 1.64-2.42]), prolonged sleep onset (SOL) (FE model=0.48 [95% CI, 0.35-0.61]), awakenings and movements (AM) (FE model=0.44 [95% CI, 0.22-0.66]), waking after sleep onset (WASO) (FE model=0.42 [95% CI, 0.22-0.62]), time in bed (TIB) (FE model=0.25 [95% CI, 0.07-0.43]), number of awakenings (NA) (FE model=0.21 [95% CI, 0.07-0.35]), and REM sleep duration (FE model=0.16 [95% CI, 0.02-0.31]).

Patients with insomnia had increased WASO (FE model=0.62 [95% CI, 0.56-0.69]), NA (FE model=0.37 [95% CI, 0.26-0.48]), SOL (FE model=0.37 [95% CI, 0.32-0.43]), and percentage of stage N1 sleep (FE model=0.27 [95% CI, 0.20-0.33]) and stage N2 sleep (FE model=0.07 [95% CI, 0.01-0.13]). Those with insomnia also had decreased sleep efficiency (FE model = -0.69 [95% CI, -0.74 to -0.64]), total sleep time (FE model = -0.57 [95% CI, -0.63 to -0.52]), REM sleep percentage (FE model = -0.26 [95% CI, -0.32 to -0.20]), and stage N3 sleep (FE model = -0.14 [95% CI, -0.20 to -0.08]).

The authors noted that their research was limited by the use of unpublished studies leading to publication bias, reliance on PSG tests, and lack of comprehensive methodologies.

The PSG profiles for insomnia attributes compared with MDD highlight the need to treat insomnia as a separate condition from MDD, not solely as a symptom. “Our work points towards the specificity of objective sleep alterations in [insomnia] that cannot be explained as a mere secondary manifestation of an affective disorder such as MDD.”

This article originally appeared on Sleep Wake Advisor