The σ bonds are usually formed by the overlap of hybridized atomic orbitals, while the π bonds are formed by the side-by-side overlap of unhybridized orbitals. Multiple bonds consist of a σ bond located along the axis between two atoms and one or two π bonds. Pi (π) bonds are formed from unhybridized atomic orbitals (p or d orbitals). Two such regions imply sp hybridization three, sp 2 hybridization four, sp 3 hybridization five, sp 3 d hybridization and six, sp 3 d 2 hybridization. We can determine the type of hybridization around a central atom from the geometry of the regions of electron density about it. These hybrid orbitals either form sigma (σ) bonds directed toward other atoms of the molecule or contain lone pairs of electrons. We can use hybrid orbitals, which are mathematical combinations of some or all of the valence atomic orbitals, to describe the electron density around covalently bonded atoms. Dipole moments can be used to determine partial separations of charges between atoms. When they overlap in a fashion that creates a node along this axis, they form a π bond. When the orbitals overlap along an axis containing the nuclei, they form a σ bond. "The changes in brain morphology seem to be temporary, but systematic comparisons between coffee drinkers and those who usually consume little or no caffeine have so far been lacking," says Reichert.Valence bond theory describes bonding as a consequence of the overlap of two separate atomic orbitals on different atoms that creates a region with one pair of electrons shared between the two atoms. "But daily caffeine consumption evidently affects our cognitive hardware, which in itself should give rise to further studies." She adds that in the past, the health effects of caffeine have been investigated primarily in patients, but there is also a need for research on healthy subjects.Īlthough caffeine appears to reduce the volume of gray matter, after just 10 days of coffee abstinence it had significantly regenerated in the test subjects. "Our results do not necessarily mean that caffeine consumption has a negative impact on the brain," emphasizes Reichert. The difference was particularly striking in the right medial temporal lobe, including the hippocampus, a region of the brain that is essential to memory consolidation. "caffeine abstinence" - the volume of gray matter was greater than following the same period of time with caffeine capsules. But they saw a significant difference in the gray matter, depending on whether the subject had received caffeine or the placebo. They also investigated the participants' sleep quality in the sleep laboratory by recording the electrical activity of the brain (EEG).ĭata comparison revealed that the participants' depth of sleep was equal, regardless of whether they had taken the caffeine or the placebo capsules. At the end of each 10-day period, the researchers examined the volume of the subjects' gray matter by means of brain scans. During one study period, they received tablets with caffeine in the other, tablets with no active ingredient (placebo). They were given tablets to take over two 10-day periods, and were asked not to consume any other caffeine during this time. Gray matter refers to the parts of the central nervous system made up primarily of the cell bodies of nerve cells, while white matter mainly comprises the neural pathways, the long extensions of the nerve cells.Ī group of 20 healthy young individuals, all of whom regularly drink coffee on a daily basis, took part in the study. However, the researchers observed changes in the gray matter, as they report in the journal Cerebral Cortex. The result was surprising: the caffeine consumed as part of the study did not result in poor sleep. Carolin Reichert and Professor Christian Cajochen of the University of Basel and UPK (the Psychiatric Hospital of the University of Basel) investigated this question in a study. So can regular caffeine consumption affect brain structure due to poor sleep? A research team led by Dr. Sleep deprivation can in turn affect the gray matter of the brain, as previous studies have shown. However, it can disrupt our sleep if consumed in the evening. No question - caffeine helps most of us to feel more alert.
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