For example, if one was travelling from Seattle to New York City and the flight arrived at 5pm New York Time the person's internal clock would still be registering 2pm. If the person wanted to be asleep around 11pm, then they should take the melatonin at about 8-830pm. If that same person flew from Seattle to Hawaii, and they arrived at 7pm, their internal clock would register 10pm; so they would still want to take melatonin based on the time they want to sleep in the local area. 3. When cats are deprived of REM sleep, longer periods of deprivation -- up to about 25 days -- are associated with greater rebound of REM when they can sleep uninterrupted. However, REM deprivation for more than 25 days produces no additional rebound. Speculate on a possible explanation. (Hint: Consider what happens to PGO waves during REM deprivation.)

REM sleep, or Rapid Eye Movement Sleep, is a normal sleep stage that includes rapid movements of the eyes, lower muscle tone (relaxation) and a low-voltage EEG. In humans in comprises about 25% of sleep, usually closer to morning. These low-voltage wages are called PGO (pons-geniculate-occipital). The loss of REM sleep due to deprivation causes a rebound,...

However, after 25 days there is no additional rebound. This is likely because there is a threshold level at which the body is able to compensate for a lack of sleep. In sleep deprived animals, PGO activity occurs earlier, and in severely deprived animals it might show up during awake time as a hallucination. The lack of additional rebound is probably a fail-safe mechanism that protects the brain chemistry of the animal.
4. Why would it be harder to deprive someone of just NREM sleep than just REM sleep?

NREM is Non-Rapid Eye Movement sleep. In NREM there is little dreaming and the muscles are not as relaxed. People who have a hard time sleeping likely get stuck in NREM sleep, in which the mental activity is more realistic, while REM sleep has more hallucinatory content. In NREM sleep the mindset of the person remains more organized, and is usually at the beginning of sleep. When a person is sleep deprived, the body sends it into REM sleep quicker, likely to help recover from the deprivation. It would be more difficult to deprive them of just NREM sleep since the cycle would reset based on the amount of…