Some sleep problems....

Delayed sleep phase syndrome is a mismatch between a person’s sleep-wake cycle to that of the general population. Most of us sleep between 10 pm to 12 midnight and wake up between 5 am to 7am.
But a person with this condition is not able to sleep till 2 am or 3 am. He is awake and mentally active till this time, showing no signs of exhaustion or sleepiness. He is able get up without feeling sleepy only bi 11 am or 12 noon.
There are many explanations for the development of this condition. One is that the sufferer’s brain is unable to respond to the most important regulator of our sleep – wake cycle i.e. light. The brain areas controlling the sleep – wakefulness cycle do not respond to the diminishing daylight to induce sleepiness. In majority of us this is why we feel sleepy when the lights are dimmed.
Need for sleep varies between individuals, and within the individual at different points in life. People with need for longer sleep may be dissatisfied even after sleeping for 9 to 10 hours. People with mood disorders – both unipolar depression and bipolar disorder – show abnormalities of sleep. Many of the bipolar patients in depressed phase, and those with a subtype of unipolar depression called atypical depression sleep for long hours.