40 years old forgetfulness is particularly strong, may be related to long-term sleep deprivation, may also be due to brain diseases, neurasthenia, iron deficiency anemia and other reasons. 1. Long-term sleep deprivation: due to long-term excessive late-night sleep, resulting in insufficient sleep, the brain for a long time did not get enough rest, resulting in his brain dysfunction, may show forgetfulness is particularly strong, but also can be accompanied by inattention, mental fatigue and other symptoms. 2. Brain diseases: such as cerebral infarction, toxic encephalopathy, cerebral blood supply insufficiency, Alzheimer’s disease, etc., the symptoms of amnesia may appear, and may be accompanied by hemiplegia, cognitive behavioral abnormalities and other symptoms. 3. Neurasthenia: this disease is mainly caused by long-term psychological stress, which can lead to mental excitability, brain fatigue, and often make the patient combined with sleep disorders, there may be forgetfulness, slow reaction and other symptoms. 4. Iron deficiency anemia: due to the reduction of peripheral blood erythrocytes, resulting in poor blood oxygen capacity of the body, resulting in the brain in a long time in a chronic ischemia, hypoxia state, it is easy to cause forgetfulness, but also can be accompanied by physical weakness, pale and other symptoms. The 40-year-old forgetfulness is particularly strong, but also for other reasons, should be as early as possible to seek medical attention, clear causes, by the doctor under the guidance of treatment.