It's very natural to wake up briefly while sleeping. In fact, most people experience a few brief awakenings during the night, even though they may not remember them in the morning.
This phenomenon, known as arousal, usually lasts for a few seconds and is a normal part of the sleep cycle.
During a typical night's sleep, a person goes through several sleep cycles, each of which includes several stages of sleep, including light sleep, deep sleep, and REM sleep. Awakenings can occur between or during these stages, and they can be triggered by a variety of factors, such as noise, discomfort, or temperature changes.