All about sleep and dreams
There are basically 5 stages of sleep in a sleep cycle, categorised by the types of brain waves. Each of this cycles lasts about 90-100 minutes and recurs several times during the night.
The 1st (lasting till 10 min) and 2nd (20min) are relatively light stages, so if people are awaken during one of these stages, they often report not having been asleep at all.
The 3rd and 4th have the slowest and highest amplitude of brain waves during sleep. Brain waves during these stages are least like waking brain waves. So if people are awakened during these stages, they usually are confused and disoriented.
After 1st-4th stage, sleepers drift towards wakefulness. But instead of re-entering stage 1, they enter rapid-eye-movement(REM) sleep. During REM sleep, the sleeper's eyeballs move up and down and from left to right. REM sleep is an active stage where dreaming usually occurs. Dreams at this stage are typically longer, more vivid, more emotionally charged, and less related to waking life.
How to reset your biological clock? In the new country, you should spend as much time outside in the daylight as possible. Bright light during the day, especially in the morning, increases wakefulness. When you sleep, you should sleep in complete darkness.
Sleepwalking has a more formal term - somnambulism. Contrary to superstition, it is safe to awaken sleepwalkers.
Just to share some of my psycho knowledge. Hope it's enlightening. Wahaha.