In the article, the author develops an analysis of external and intrapsychic factors related to adults' insomnia. First she undertakes a literature review to describe semiological, evolutive and etiological levels of insomnia. From a semiological point of view, it is usual to differenciate initial insomnia (associated to the first phase of sleeping), intermittent insomnia (related to frequent awakenings) and final insomnia (related to early morning awakenings). From an evolutive point of view, we can identify transitory insomnia (characterized by frequent awakenings) and chronic insomnia. On the other hand, we are allowed to distinguish organic insomnia (disorder where an organic cerebral injury is demonstrated or suspected) from insomnias related to psychiatric or somatic disease or idiopathic one. Then, the author makes a literary review to identify various insomnia causes and points out. Social factors: insomnia rates are higher by divorced, separated or widowed people. Percentages are higher when scholastic level is weak, domestic income is less then 915 O a month, or by unemployed people. Besides, sleep quality is deteriorated by ageing. Sleeping and waking rhythm is able to loose its synchronization. Complaints about insomnia occur far frequently from women than men. Environmental factors: working constraints increase sleep disorders. It is possible to make the same conclusion when we have to face overcharge of external events, deep intrapsychic conflicts (related to grief, unemployment, damage or hospitalization) or interpersonal conflicts' situations where we are confronted to stress related to socio-affective environment, lack of social support or conjugal difficulties. Medical and physiologic causes: legs impatience syndrome, recurrent limbs shakings syndrome, breathe stop during sleep, narcolepsy, excessive medicine or hypnotic drugs use, some central nervous system injuries, every nocturnal awakening (related to aches.), surgical operation. Chronobiological factors: night working or day-night shift produce insomnia by desynchronization. It is the same for time lag related to jet-lag flights. Significant gaps between the internal biological clock and environmental synchronizators, such as phase delay sleep, phase advance sleep, sleep-waking cycle longer than 24 (25) hours, or variations in sleep-awakening cycle, are of less importance. Toxic factors are numerous: amphetamines, antidepressors, medication against anorexia and tubercular disease, caffeine and alcohol excessive use, chronic alcoholism. Behavioral factors: enduring insomnias are related to poor nightroutines (to go to sleep too early, to read or to look at T.V. when going to bed). The same effect is produced by regular intellectual activities close to bedtime or by a late meal in the evening, by an noisy or unhealthy environment, by physical hyperactivity or sleeping after each lunch. Psychiatric factors: insomnia often appears with psychiatric disorders such as a major depressive episode, an anxiety disorder or schizophrenia. Insomnia also is able to open a delirious disorganization or a manic access. Psychological factors: overstimulation of waking system (related to stress overdose or intellectual hyperactivity), conditioning phenomena, fear of not falling asleep, intrapsychic and interpersonal conflicts. Third, the author put hypothesis about psychodynamic etiology of chronic insomnia. Following a first assumption, insomnia should be a result of anguish excess related to intrapsychic (and not interpersonal) conflicts which can't lead to a mental elaboration. These conflicts run over dream protective function, generating a breakdown of dream symbolization function. At a clinical level, we are in some cases in front of people enduring sleeping insomnia but more often, we are confronted with an intermittent or early waking insomnia sometimes associated with nightmares. Following a second assumption, insomnia should be a result of psychic functioning invalidation. Here, failure of dream protective and symbolization function is related to anguish excess associated with an amount of external conflicts. Overwhelmed by concretude, insomniac patients present an alexythimic intrapsychic functioning forbiding dream realization. These persons have no possibility to elaborate conflicts especially external overcharge, using dreams or imagination to escape from an intrusive reality and regress to sleeping. Here we are in front of initial sleep insomnia. Following a third hypothesis, some insomnias are related to wakings associated with repetitive nightmares. This type of insomnia should be related to a past traumatic event or activated by actual existential context and produces a too important anguish charge to follow a mental elaboration process and lead to mental symbolic representation. Following a fourth hypothesis, some insomnias are in relation with an impossibility to accept passive position. The last one will expose to a danger consisting either of castration or loneliness and death. To conclude, the author suggests some preventive perspective to face insomnia. Especially, she points out limits of pharmalogical treatments. She underlines the necessity to promote no medical methods to facilitate sleep induction and maintenance, including sleep hygiene measures, relaxation, psychotherapic approach and behavioral methods. She emphasizes the danger of a reductive approach of insomnia which would be focused on a single medical, psychological or environmental dimension. Last but not least, she makes methodological propositions to test from a clinical point of view the four psychodynamic exposed hypotheses.