NightSwimmer
Senator
I sometimes do. I don't always notice it, but my wife usually does. Some say that it can trigger that falling sensation that happens sometimes while you're falling asleep.
Wikipedia:
A hypnic jerk, hypnagogic jerk, sleep start, or night start, is a myoclonic twitch which occurs during hypnagogia, just as a person is beginning to fall asleep, often causing them to awaken suddenly for a moment. Physically, hypnic jerks resemble the "jump" experienced by a person when startled, often accompanied by a falling sensation. A higher occurrence in people with irregular sleep schedules is reported.
Wikipedia:
A hypnic jerk, hypnagogic jerk, sleep start, or night start, is a myoclonic twitch which occurs during hypnagogia, just as a person is beginning to fall asleep, often causing them to awaken suddenly for a moment. Physically, hypnic jerks resemble the "jump" experienced by a person when startled, often accompanied by a falling sensation. A higher occurrence in people with irregular sleep schedules is reported.