In general, it's acceptable to occasionally sleep all day, particularly if your body need more rest because of stress, sickness, or lack of sleep. While frequent or extended daytime sleep may indicate an underlying problem, such as melancholy, hypersomnia, or poor sleep quality, occasional lengthy sleep bouts might aid in the healing process. It can be worthwhile to speak with a healthcare professional if you frequently find yourself needing too much sleep or having trouble staying awake during the day. Drugs like Modalert 200 (modafinil) can assist encourage alertness and improve productivity in situations of chronic daytime sleepiness. Modalert should only be taken under a doctor's supervision, though, and long-term health depends on treating the underlying cause of sleep problems.