Despite the stunning amount of research on sleep and emotion, we still understand the neurochemical functions of the human brain only at the most rudimentary level. How do chemical interactions govern our mood? Our wakefulness? What triggers the release of certain neurochemicals? The answers are still mostly unknown.
New Research, New Hope
For the first time, UCLA researchers have identified a specific peptide that increases substantially when study subjects were happy, and decreases noticeably when the same subjects are sad. The neurochemicals, called hypocretin, may serve to increase both mood and alertness and humans, and so the new findings could have implications for the treatment of psychological disorders like depression, as well as sleep problems like chronic tiredness. By targeting particular abnormalities in brain chemistry doctors may be able to alleviate multiple symptoms.
The study, published in the online edition of Nature Communications, also found that melanin concentrating hormone (MCH), another measurable peptide, was only minimally present during waking but drastically increased during sleep, implicating the neurochemical with a strong role in human drowsiness.
Narcolepsy, Depression, and Sleep
MCH and hypocretin together may explain the well-documented interaction between narcolepsy and depression.Senior author Jerome Siegel, director of the Center for Sleep Research at the Semel Institute at UCLA, told Science Daily the findings “suggest that hypoctreting deficiency ay underlie depression from other causes,” too.
The study’s sample size is small but the study was certainly thorough – eight patients with a microchip implant were monitored day and night and answered questions about mood and attitude every hour during periods of wakefulness. The results? Hypocretin levels were highest at waking, periods of positive emotion, anger, and social interaction. MCH, on the other hand, was highest at the time of falling asleep and lowest during social interaction. The results suggest there may be more of an emotional effect on arousal or sleepiness than doctors previously thought.
Hypocretin antagonists are currently under development as sleeping pills. According to this study, drugs that affect hypocretin should alter mood as well as sleepiness. Boosting hypocretin may elevate mood, making it a potentially effective antidepressant.
What do you think? Are emotions and sleepiness linked?