The wakefulness-promoting drug armodafinil, which is marketed under brand names including Waklert 150, is frequently given for ailments like narcolepsy, shift work sleep disorder, and exhaustion brought on by sleep apnea.  Certain brain areas that control wakefulness and alertness are stimulated by it.  As a result, if armodafinil is taken too late in the day or in excess, it may make it difficult to fall asleep.  Although it doesn't actually "stop" you from sleeping, it can shorten your sleep duration and postpone the beginning of sleep.  Doctors often advise avoiding coffee later in the day and taking Waklert 150 in the morning to reduce sleeplessness.