Meditation and sleep are hypometabolic states, in which breathing and other bodily activities decrease. Both release stress, but the rest that meditation provides is much deeper than the rest that comes from sleep. Therefore, the most entrenched impressions, or samskaras, leave the system. What if there was an alternative? Research shows that meditation can replace sleep.
Instead of trying to incorporate it into your normal day, you can try meditating instead of sleeping. The researchers found that sleep reduction is quite common during times of intensive meditation practice, such as multi-day silent retreats. In fact, according to some Buddhist texts, a full night's sleep amounts to approximately four hours among competent meditators. These subjects had a sufficient amount of daily meditation time so that it could produce a noticeable decrease in total sleep time if meditation can actually replace part of sleep or compensate in some other way.
If this is your case, it could mean a few different things, including that you need more sleep, plain and simple. Perhaps there is a basic amount of sleep that is fundamental for all mammals (and perhaps also for all or most non-mammals) and it cannot be replaced by anything other than sleep. There is further investigation into whether meditation can actually replace part of sleep or pay off sleep debt. The restorative alertness that you can experience with meditation is associated with a decrease in heart rate, a decrease in metabolism, and changes in the nervous system that reduce the arousal that occurs during sleep.
But what about the stories of the ancient yogi who meditates in a cave or in a monastery on the top of a mountain for days and weeks without sleep? How does he do it? While expert meditators are able to go so deep that you no longer need sleep, it takes incredible skills to do so. The key distinction between meditation and sleep is being alert during meditation and not being alert during sleep.