Insomnia is the inability to fall asleep or stay asleep, resulting in sleep deprivation. It is a common disease caused by various reasons such as difficulty in falling asleep, short sleep depth or frequency, early awakening and insufficient or poor quality sleep time. What are the manifestations of insomnia? The following are the manifestations of insomnia. 1.Difficulty in falling asleep. 2.Waking up early and not being able to fall back to sleep after waking up. 3.Energy is not restored after sleeping. 4.Inability to sleep well and reduced sleep time. 5.The onset time can be long or short, short days to get better, long days to recover. 6.Easy to be awakened, some are sensitive to sound, some are sensitive to light. 7.Frequently wake up from nightmares, and feel that they are having nightmares all night long. 8.Many insomniacs like to think nonsense. 9.Long-term insomnia can lead to neurasthenia and depression, and neurasthenia patients’ illnesses can aggravate insomnia. University of Pennsylvania researchers and their British counterparts published a paper in the journal that they deprived experimental rats of five hours of sleep in the experiment. The results revealed an increase in the amount and activity of an enzyme called PDE4 in the brains of the lab rats, which affects the molecules that help retain memory, thus weakening it. Further experiments revealed that with the use of a related drug that can inhibit this enzyme, the sleep deprived lab rats no longer experienced memory loss. This suggests that effective drug treatment options could be found on this basis to help those suffering from insomnia to improve their memory.