Hello, The main active ingredient in marijuana is 9-Tetrahydrocannabinol (THC). When marijuana is metabolized in the body, it produces different metabolites, some of which are quite sedative. These metabolites make you feel tired after the high effect of marijuana is over and it starts leaving your system. The phenomenon you experience as tiredness and sleepiness is also called crash . Furthermore, many varieties of marijuana are high in myrcene. This myrcene has high sedative properties when they combine with THC component of marijuana bringing the effects of tiredness and sleepiness when smoked. Marijuana addiction has both short and long term adverse effects on various systems of the body including physical and psychological. Short-term effects include altered senses, altered sense of time, mood changes, altered memory and inability to make decisions or focus to think in one direction. However, long-term effects of this addiction are more debilitating. These effects may last forever becoming permanent and irreversible. Lungs feel constantly irritated due to smoke of marijuana which leads to permanent damage to lungs causing breathing problems and frequent sicknesses related to lungs. Heart rate increases up to 3 times after smoking marijuana increasing chances of heart attack, sudden cardiac arrest resulting in collapse and sudden death. It can also cause permanent damage in brain causing seizures, depression and anxiety disorders. To conclude, marijuana addiction can lead to poor life satisfaction, impaired physical and mental health along with social and relationship problems. It is advisable to quit this habit as soon as possible. You can quit it with help of a mental health professional or psychiatrist who can watch for symptoms post cessation and can help you accordingly with counselling sessions and medications. I hope this information helps. Thank you for choosing HealthCareMagic. Take care. Best, Dr. Viraj Shah