CIRCADIAN RHYTHM DISORDERS
Delayed-sleep-phase syndrome is a disorder in which nightly sleep is delayed until long after the desired sleep time (not before 2:00 a.m.). This results in sleep onset association disorder, excessive daytime sleepiness and trouble waking up at the desired time (not before 10:00 a.m.).

Advanced-sleep-phase syndrome is a disorder in which nightly sleep and irresistible sleepiness come before the desired time (between 6:00 and 9:00 p.m.). The patient wakes up earlier than desired (2:00 to 5:00 a.m.) in the morning.

Other circadian rhythm disorders are Jet lag syndrome, shift-work sleep disorder, irregular sleep-wake rhythm syndrome and 24-hour sleep-wake syndrome which are classified as sleep and circadian rhythm disorders, too.

There are diseases associated with sleep and circadian rhythm disorders like mood disorders, seasonal affective disorders (SAD), chronic fatigue syndrome (CFS), chronic sleep onset insomnia in children with the so called attention deficit hyperkinesias disorder (ADHD) that manifest similar sleep disturbances.

MELATONIN AND CIRCADIAN RHYTHM DISORDERS
Melatonin plays an important role in the synchronisation and characterisation of sleep-wake cycles. Endogenous melatonin is a hormone produced in the pineal gland during the dark phase of the day-night cycle. Its secretion is controlled by an endogenous oscillator that is entrained by light. Daytime melatonin levels are low or even undetectable and rise in the evening during decreasing light intensity.

The onset point of melatonin secretion under dim light conditions is called DLMO (Dim Light Melatonin Onset). In contrast to other circadian markers like cortisol, melatonin is the preferred circadian marker because of its robustness even in the presence of various exogenous factors like mental pressure or others.

DIM LIGHT MELATONIN ONSET
DLMO is considered to be the most useful parameter of the 24 hour melatonin curve and is the recommended parameter to diagnose sleep and circadian rhythm disorders. The easiest way to assess the DLMO, melatonin can be determined in saliva samples collected by the patient himself.

In most cases, it‘s not necessary to determine a 24 hours profile which is more difficult to collect. In fact, a partial melatonin profile, composed of 5 saliva sample collected hourly around bed time is sufficient to asses DLMO (see Sleep Check). In adults the normal DLMO time points are around 07:30 p.m. to 10:00 p.m. An abnormal timing of DLMO indicate a sleep and circadian rhythm disorders and provides a clue for the optimal timing of treatment with exogenous Melatonin or bright light.

MELATONIN IMMUNOASSAYS
BÜHLMANN offers most sensitive Immunoassays to measure any kind of biological sample by either RIA or ELISA technique. Because Melatonin is a conservative molecule, its immunological quantification is not restricted to humans alone. Even plants synthesises this hormone.

	ALL SPECIMEN	SALIVA		URINE
		Melatonin	Direct Saliva Melatonin	Direct Saliva Melatonin	6-Sulfatoxy Melatonin
Test System	RIA	RIA	ELISA	ELISA
Sample Volume	800 µl	800 µl	200 µl	10 µl
Sample Preparation	EXTRACTION	DIRECT	PRE- TREATMENT	DIRECT
Time to Result	24 h	24 h	24h	4.5 h
Standard Range	0.5 - 50 pg/ml	0.5 - 50 pg/ml	0.6 - 25 pg/ml	0.8 - 40 ng/ml
Order Code	RK-MEL2	RK-DSM2	EK-DSM	EK-M6S

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