Afternoon serum-melatonin in sleep disordered breathing

Area of Science:

• Endocrinology
• Sleep Medicine
• Circadian Biology

Background:

• Melatonin, a hormone with a strong circadian rhythm, exhibits high nocturnal and low afternoon levels.
• Sleep disordered breathing (SDB) may disrupt the natural circadian rhythm of melatonin, potentially offering diagnostic insights.
• Afternoon serum-melatonin levels may serve as a biomarker for circadian rhythm disturbances in SDB.

Purpose of the Study:

• To investigate afternoon serum-melatonin levels in patients diagnosed with sleep disordered breathing.
• To explore the potential diagnostic implications of altered melatonin circadian rhythms in SDB.
• To assess the relationship between SDB, melatonin levels, and daytime sleepiness.

Main Methods:

• Sixty consecutive patients with SDB and ten healthy controls were evaluated.
• Sleep apnoea screening utilized a combination of static charge sensitive bed and oximetry, achieving 100% specificity for obstructive sleep apnoea syndrome (OSAS).
• Afternoon serum-melatonin levels were measured, and daytime sleepiness was assessed using the Epworth Sleepiness Scale.

Main Results:

• Patients with OSAS demonstrated significantly elevated afternoon serum-melatonin levels compared to healthy controls.
• Serum-melatonin testing for OSAS in SDB patients yielded low sensitivity but high specificity.
• The findings suggest that sleep breathing disorders generally impact pineal gland function.

Conclusions:

• Sleep disordered breathing appears to disrupt normal pineal gland function.
• Afternoon serum-melatonin levels, even when combined with daytime sleepiness scores, are insufficient for identifying OSAS in a mixed population presenting with snoring and excessive daytime sleepiness.