Pineal Gland Volume, Sleep Quality, and Psychiatric Disorders: A Systematic Review and Meta-Analysis

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Sleep and circadian rhythm disturbances are common in psychiatric disorders.
• The pineal gland regulates circadian rhythms via melatonin.
• Pineal gland volume (PGV) is a structural proxy for pineal gland function.

Purpose of the Study:

• To synthesize evidence on PGV differences between psychiatric patients and healthy controls.
• To examine the association between PGV and sleep outcomes.

Main Methods:

• Systematic literature searches of major databases (PubMed, Embase, Scopus, Web of Science).
• Quality assessment using the Newcastle-Ottawa Scale.
• Random-effects meta-analyses (REML) for group comparisons and correlations.
• Subgroup analyses by diagnostic category.

Main Results:

• PGV was significantly lower in psychiatric patients (n=1055) vs. controls (n=712) (g=-0.54).
• Reductions were most pronounced in schizophrenia spectrum disorders (g=-0.63).
• The association between larger PGV and better sleep was weak and nonsignificant (Zr=0.18), with high heterogeneity.

Conclusions:

• Reduced PGV is a common finding across psychiatric disorders, particularly schizophrenia spectrum disorders.
• This reduction may represent a trait-like structural alteration associated with psychiatric illness.
• Current evidence does not conclusively link PGV to sleep disturbance severity.