A good night's sleep: How much is too much?

Q Will someone suffer depression or become sick due to too much sleep? I have been sleeping on average 10 hours a night for the last two weeks. Does the human body react to sleeping too much?

I am 25 years old this year. I am aware that the average length of sleep for people in my age group is five to seven hours.

What would be the symptoms if I am suffering from something? Please advise me.

A An average person usually sleeps between seven and eight hours a night, but there is a great deal of variation in each individual's sleep requirements, which can vary from three to 11 hours a night in completely normal individuals. The best guide to your own sleep requirement is to see how much you sleep when you are well rested and are not constrained to a particular sleeping time or waking hour - for example, when you are on holiday, or over a weekend. Another good clue to whether your sleep is normal is how you feel when you wake up - If you are rested and refreshed, then the duration of sleep is appropriate for you.

Sleeping 10 hours a night is not harmful to your health, especially if this is your usual sleep requirement. However, if you find that you are sleeping much more than usual and are still tired, this may be a sign of underlying health problems such as depression or other organic disorders.

Usually, there will be associated systemic symptoms in this case - Are you losing weight? Is your appetite normal? Are your bowel movements, urinary habits and menstruation patterns normal?

Alternatively, it may be a sign that there is a primary sleep disorder such as obstructive sleep apnoea, restless legs syndrome or idiopathic hypersomnolence, which is causing the sleep to be non-restful. Sleeping longer hours than usual is usually a result of the underlying disorder rather than the cause per se.

Unless you are on medication or anaesthetised, it is actually not possible to sleep 'too much'. The brain has powerful regulatory mechanisms which determine your sleep-wake cycle. If you have slept enough to meet your intrinsic sleep requirement, you will not be able to sleep no matter how hard you try. If you have a small sleep debt, you can stay awake with very little stimulation. If you have a very large sleep debt, you will fall asleep no matter how hard you try to stay awake.