Asthma is often worse at night or in the early morning hours. The typical age of diagnosis for narcolepsy is 40 years or older. The chief complaint in children with obstructive sleep apnea is daytime sleepiness. Melatonin is a natural body hormone that decreases at the beginning of sleep. Slow wave sleep is more prominent in the second half of the night.
Nightmares typically occur during REM sleep.
The amount of slow wave sleep increases over 50 years of age. Episodes of sleepwalking tend to occur in the last third of the night. Episodes of REM sleep tend to shorten throughout the night. Children who experience night terrors usually have emotional problems. Periodic limb movements during sleep are often increased in REM sleep.