First night effect in depression: new data and a new approach

Area of Science:

• Neuroscience
• Sleep Medicine
• Psychiatry

Background:

• Depression is often associated with sleep disturbances.
• The first-night effect (FNE) in polysomnography (PSG) is a common phenomenon where sleep patterns on the first night in a lab differ from subsequent nights.
• The clinical significance of FNE in depressed patients remains unclear.

Purpose of the Study:

• To investigate the relationship between the first night effect and sleep architecture in depressed patients.
• To explore whether the FNE reflects adaptive physiological responses in depression.

Main Methods:

• Polysomnography (PSG) was conducted for 2-3 consecutive nights in 20 depressed patients and 8 healthy controls.
• Patients were categorized into two groups based on the presence (Group I) or absence (Group II) of a first night effect (defined as a ≥30 min longer REM sleep latency on night 1 vs. night 2).
• Groups were matched for age, gender, and depression severity.

Main Results:

• Group I (with FNE) exhibited significantly shorter REM sleep latency on nights 2 and 3 compared to Group II.
• REM sleep percentage increased from night 1 to night 2 in Group I.
• A prominent shift of REM sleep to the first cycle occurred on night 1 only in patients with FNE.
• Delta sleep was preserved in Group I compared to Group II.

Conclusions:

• The first night effect in polysomnography may represent a physiological system's enhanced capacity for adaptive response and homeostasis maintenance under environmental stress.
• FNE in depressed patients is associated with specific alterations in REM sleep architecture, particularly a shift towards earlier REM.
• These findings suggest FNE could be a marker of resilience or adaptive capacity in the context of depression.