“A gentleman of my acquaintance in whose family circumstances had occurred which were to him sources of intense anxiety, passed six entire days and nights without sleep. At the end of this time he became affected with illusions of such a nature that it was necessary to place him in confinement. After some time he recovered perfectly. He had never shown any signs of mental derangement before, nor has any one of his family, and he has never since been similarly affected. This was an extreme case. But do not examples of the want of sleep, proving very similar results, though in a very much less degree, occur under our observation constantly? How altered is the state of mind in any one of us after even two sleepless nights! Many a person who under ordinary circumstances is cheerful and unsuspicious, becomes not only irritable and peevish, but also labors under actual, though transitory, illusions; such, for example, as thinking that others neglect him or affront him who have not the smallest intention of doing either the one or the other.” Cases similar to the following, which is one of the passive variety of wakefulness, are by no means uncommon. CASE IV.--A lady, aged about thirty-five, unmarried, and of rather delicate constitution, consulted me in regard to persistent wakefulness, with which she had been affected for nearly a month. According to the account which she gave me, she had received a severe mental shock, which had not lost its influence when a subject of great anxiety was forced upon her consideration. Her menstrual period, which had been due about ten days before she came under my notice, had been anticipated by a week, and the flow was prolonged much above the ordinary time. She had, therefore, lost a good deal of blood, and was, in consequence, greatly reduced in strength. This, conjoined with the exhaustion due to the long-continued wakefulness, rendered her condition a much more serious one than would otherwise have been the case. She had taken large doses of laudanum, of ether, and of valerian, together with many other medicines, the names of which I do not now recollect, besides employing a variety of means of traditional efficacy. All had, however, been useless. Homœopathy was then tried with an equal want of success. When I first saw her she was nervous and irritable, her hands trembled violently upon the slightest exertion of their muscles, her eyes were bloodshot, the pupils contracted, and the lids opened to the widest possible extent. There was a constant buzzing in the ears, and the sense of hearing was much more acute than was natural. There was also increased sensibility of all that portion of the surface of the body (the skin of the hands, arms, legs, back, and breast) which I submitted to examination with the æsthesiometer. Her pulse was 98, irritable, small, and weak.