Pokemon Go made billions of dollars getting people to roam the great outdoors. Now, the company behind the global game phenomenon is trying to get people to go to bed.

Pokemon Sleep records and rewards your sleep with Pokemon that you’d otherwise have to spend many waking hours catching. Developed by Japanese games studio Select Button Inc. and published by The Pokemon Co., Pokemon Sleep was the most downloaded game during the week starting July 16, according to mobile data analytics firm data.ai. The game celebrated hitting 10 million downloads Friday by offering some in-game items for free.

Users play by sleeping with their smartphones close to their heads, and the game keeps track of vibrations caught by the phones’ sensors to estimate sleep quality. The better your sleep metrics, the more creatures you collect.