Effects of high frequency rTMS on sleep deprivation: A pilot study.

Transcranial magnetic stimulation is a neurostimulation technique which has the potential to serve as a unique research tool for investigating a wide variety of fields in cognitive neuroscience. TMS has been approved by the FDA to serve as a treatment to depression and has also been used to evaluate its effects among several conditions such as Alzheimer, Parkinson disease, chronic pain and stroke. High frequency TMS has been previously used with the intention to measure and modulate the negative effects of sleep deprivation in cognitive performance, but there is no consensus about the ideal protocol yet. In this pilot study, we attempt to test high frequency rTMS in different brain targets in order to determine the effects in remediation of working memory due to sleep deprivation. These results provide preliminary evidence of the potential effectiveness of TMS for the treatment of cognitive impairment.

Steroid hormones and sleep regulation.

In the search of the sleep substance, many studies have been addressed for different hormones, responsible for sleep-wake cycle regulation. In this article we mentioned the participation of steroid hormones, besides its role regulating sexual behavior, they influence importantly in the sleep process. One of the clearest relationships are that estrogen and progesterone have, that causing changes in sleep patterns associated with the hormonal cycles of women throughout life, from puberty to menopause and specific periods such as pregnancy and the menstrual cycle, including being responsible for some sleep disorders such as hypersomnia and insomnia. Another studied hormone is cortisol, a hormone released in stressful situations, when an individual must react to an extraordinary demand that threatens their survival, but also known as the hormone of awakening because the release peak occurs in the morning, although this may be altered in some sleep disorders like insomnia and mood disorders. Furthermore neurosteroids such as pregnanolone, allopregnanolone and pregnenolone are involved in the generation of slow wave sleep, the effect has been demonstrated in experimental animal studies. Thus we see that the sleep and the endocrine system saved a bidirectional relationship in which depends on each other to regulate different physiological processes including sleep.

Polysomnographic features in infants with early diagnosis of congenital hypothyroidism.

Thyroid hormones play a major role in the maturation process of the brain. Currently, congenital hypothyroidism is detected by mass screening. The impact of this early hormonal deficiency on the organization of the sleep pattern is not known. In this study, the polysomnographic features in children diagnosed with congenital hypothyroidism were analyzed. Children were detected by mass population screening and the hormonal replacement therapy starts immediately. Children's age ranged between 1.5 and 18 months of age. The duration of hormonal treatment before sleep recordings varied between 8 days and 17 months. Children were polysomnographically recorded in the morning, for at least 2h, obtaining more than one sleep cycle. Results showed a high prevalence of females (5/1) in the group studied. A high proportion of infants (43%) displayed central apnea in different degrees (mild, moderate and severe) as well as hypopnea (83%), mainly in subjects around 4 and 8 months of age. The proportion of infants displaying central apnea decreases as age increases. In addition, indeterminate (light) sleep increase and quiet (slow wave) sleep decrease significantly regardless of age and treatment. The percentage of REM sleep correlated positively with the age of the child at the beginning of the treatment, and negatively with their age at the time of the study. These data indicate that congenital hypothyroidism facilitates the presence of central sleep apnea. The decrease of these respiratory alterations correlates with the increase of the hormonal replacement therapy. It seems that sleep respiratory alterations in congenital hypothyroidism are linked to brain maturation processes in which thyroid hormones play a major role.