Poor sleep quality is associated with symptom severity in schizophrenia, including later illness onset, independent of chronotype or BDNF Val66Met variant.
Poor sleep quality was highly prevalent in schizophrenia, affecting over two-thirds of patients.
Poor sleep quality was significantly associated with greater symptom severity across all PANSS domains.
Schizophrenia patients with poor sleep quality had a later age of illness onset.
Morning chronotype was associated with longer illness duration but lower general psychopathology scores.
The BDNF Val66Met genetic variant showed no association with sleep quality, chronotype, or symptom severity.
Plasma BDNF levels were higher in poor sleepers, independent of Val66Met genotype.
The association between poor sleep quality and symptom severity in schizophrenia is independent of both chronotype and BDNF Val66Met genotype.
This research suggests that poor sleep quality is extremely common among people with schizophrenia—nearly 70% of the 217 patients studied were classified as poor sleepers—and that sleeping poorly is strongly linked to worse psychiatric symptoms across all symptom domains, including positive symptoms (like hallucinations and delusions), negative symptoms (like social withdrawal), and general psychopathology. Patients with poor sleep also tended to develop schizophrenia later in life. These findings held up even after accounting for whether patients were naturally 'morning' or 'evening' types and for a specific gene variant (BDNF Val66Met) that has been thought to influence both sleep and brain health. Interestingly, while a specific genetic variant (BDNF Val66Met) did not appear to affect sleep or symptoms, the actual measured protein levels of BDNF in the blood were significantly higher in poor sleepers, with a strong correlation. This suggests that while the inherited genetic variant may not matter much, the biological activity of BDNF itself may still play a role in sleep disturbances in schizophrenia. Patients with a morning chronotype tended to have been ill longer but had milder general symptoms, suggesting that body clock preferences may relate to illness course in complex ways. This research suggests that sleep quality is an important and somewhat independent factor in the severity of schizophrenia symptoms, and that improving sleep could be a meaningful treatment target regardless of a patient's genetic background or natural sleep-wake preferences. The strong relationship between poor sleep and worse symptoms across all symptom domains highlights the potential value of routinely assessing and addressing sleep problems in people living with schizophrenia.
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Upload Your LabsKumar A, Shaju A, Sidharthan M, John J, Mundedath R, Haridas N, et al.. (2026). Poor sleep quality is associated with symptom severity in schizophrenia, independent of chronotype and BDNF Val66Met genetic variant.. Progress in neuro-psychopharmacology & biological psychiatry. https://doi.org/10.1016/j.pnpbp.2026.111907