Fragmented Sleep Enhances Postoperative Neuroinflammation but Not Cognitive Dysfunction.

Area of Science:

• Neuroscience
• Immunology
• Sleep Medicine

Background:

• Sleep disruption is linked to cognitive decline and dysfunction.
• Surgery triggers neuroinflammation, potentially exacerbating cognitive impairment.
• Postoperative delirium is more common in surgical patients with sleep disorders.

Purpose of the Study:

• Investigate the impact of perioperative sleep fragmentation (SF) on neuroinflammation and cognition following surgery.
• Determine if SF exacerbates surgery-induced cognitive deficits.

Main Methods:

• Adult male mice underwent 24-hour sleep fragmentation (SF) using an orbital shaker.
• Tibial fracture surgery was performed either before or after the SF period.
• Systemic and hippocampal inflammation markers (e.g., IL-6, TNF-α) and cognitive function were assessed.

Main Results:

• SF alone caused memory dysfunction and increased systemic IL-6 levels.
• SF impaired hippocampal-dependent memory recall.
• Surgery also reduced memory performance, but SF did not further exacerbate this impairment.
• Both SF and surgery increased hippocampal inflammatory markers (TNF-α, IL-6), with combined effects being more pronounced.

Conclusions:

• Perioperative SF significantly increases hippocampal inflammation but does not worsen cognitive impairment when combined with surgery.
• A dissociation between neuroinflammation and cognitive decline was observed.
• The study suggests current memory tests may not capture all cognitive aspects affected by SF and surgery.