REM sleep deprivation increases early morning pineal melatonin in castrated rats

Differential melatonin alterations in cerebrospinal fluid and serum of patients with major depressive disorder and bipolar disorder

BACKGROUND

Melatonin, which plays an important role for regulation of circadian rhythms and the sleep/wake cycle has been linked to the pathophysiology of major depressive and bipolar disorder. Here we investigated melatonin levels in cerebrospinal fluid (CSF) and serum of depression and bipolar patients to elucidate potential differences and commonalities in melatonin alterations across the two disorders.

METHODS

Using enzyme-linked immunosorbent assays, CSF and serum melatonin levels were measured in 108 subjects (27 healthy volunteers, 44 depressed and 37 bipolar patients). Covariate adjusted multiple regression analysis was used to investigate group differences in melatonin levels.

RESULTS

In CSF, melatonin levels were significantly decreased in bipolar (P<0.001), but not major depressive disorder. In serum, we observed a significant melatonin decrease in major depressive (P=0.003), but not bipolar disorder. No associations were found between serum and CSF melatonin levels or between melatonin and measures of symptom severity or sleep disruptions in either condition.

CONCLUSION

This study suggests the presence of differential, body fluid specific alterations of melatonin levels in bipolar and major depressive disorder. Further, longitudinal studies are required to explore the disease phase dependency of melatonin alterations and to mechanistically explore the causes and consequences of site-specific alterations.

Sleep deprivation therapy in depressive illness and Parkinson's disease

1. Sleep deprivation is commonly associated with feelings of fatigue and cognitive impairment. 2. Patients with depressive illness, however, often experience mood improvements under these same conditions. 3. Other studies now show that tremor and rigidity, in patients with Parkinson's disease, are also improved by sleep depression therapy. 4. The neural substrates which underlie these effects are unclear. Some recent evidence, however, suggests that sleep deprivation may activate mechanisms which are otherwise typical of conditions of metabolic stress. 5. A common feature of these mechanisms is the suppression of cholinergic activity which is thought to be excessive, in relation to monoamine transmission, in both depression and Parkinson's disease.

Is Alzheimer's disease related to a deficit or malfunction of rapid eye movement (REM) sleep?

Current theories of the cause of Alzheimer's disease (AD) do not address the question as to why AD patients initially and gradually lose their short-term memory, followed later by progressive and accelerated loss of other memory, language, motor skills, perception and very short-term memory. We propose that this pattern of memory loss may be a result of a REM sleep deficit or malfunction. This hypothesis is also supported by: 1) Results which show that AD patients have less REM sleep than controls. 2) There is an established close correspondence between learning/memory and REM sleep. REM sleep deprivation is known to result in impairment in learning recent information. 3) AD patients have a degenerated cholinergic system of the brain. The cholinergic system is known to activate/stimulate the REM sleep process. 4) The lesions in AD victims are primarily located in those regions of the brain that are considered to be active during REM sleep. 5) There is a natural mechanism by which the REM sleep in humans is reduced from 8 hours each day at birth to less than 1 hour each day in old age. An acceleration of this process can lead to possible REM deficit at old age. Furthermore, since old people have so little REM sleep they are more vulnerable to a REM sleep deficit. The REM sleep deficit mechanism may also work in conjunction with other theories of the etiology of AD, in which case, the REM sleep deficit may explain the progression and/or the acceleration of memory loss in AD.(ABSTRACT TRUNCATED AT 250 WORDS)

Indole-3-pyruvic acid as a possible hypnotic agent in insomniac subjects

In a single-blind study six male patients (mean age 39.5 years) with moderate insomnia were treated with placebo for three nights, 100 mg indole-3-pyruvic acid (IPA) for three nights, 200 mg IPA for three nights, 100 mg IPA for two nights and placebo for two nights. Polygraphic recordings were made and total sleep time, sleep efficiency, sleep latency, slow wave sleep latency, rapid eye movement (REM) sleep latency, number of arousals (greater than 1 min), percentage and duration of wakefulness after sleep onset, percentage and duration of wakefulness after sleep onset, percentage and duration of sleep stages 1, 2, 3, 4 and REM were recorded. At the end of 13 days, total sleep time, duration of stage 2 sleep and total non-REM were significantly increased when compared with baseline. Total sleep time and duration of stage 2 and total non-REM sleep on completion were significantly decreased when compared with after 200 mg IPA (night 9). Results suggest an action of IPA on human sleep similar to that of exogenous melatonin and L-tryptophan, thus confirming that IPA could be used to increase serotonin and melatonin turnover.