In Edinburgh, Ian Oswald reported in 1966 the case of six medical students who went into sleep deprivation for 108 hours or 4.5 days. When the experiment was terminated, and they finally went to sleep, they slept for an average of 12 to 14 hours straight.

The above studies appear to contradict what we normally estimate as the amount of sleep required. If we normally sleep 7 hours each 24 hours, then Tripp who did not sleep for 8.33 days would need 58.31 hours sleep to catch up; Gardner who did not sleep for 11 days would need 7 7.00 hours to recuperate; and the Oswald’s students who did not sleep for 4.5 days would need 31.50 hours sleep.

Does this imply that we need only a minimum of two to three hours sleep each day, and the rest of the time that we spend sleeping is a waste or a luxury? Of course not; we must remember that

during sleep deprivation these subjects were not functioning well. Tripp was hallucinating, Gardner had heavy and tired eyes, and Oswald’s students were not enjoying the experience one bit. Hence two to three hours sleep each day is not sufficient for normal healthy functioning.

However, we can draw a few important conclusions from the above sleep deprivation reports.

* After a few sleepless nights, we do not need the same number of hours sleep that we had missed out on to recuperate. A few hours more than the normal sleep period is sufficient to feel refreshed and well again. In other words, we do not need to pay back the sleep debt we create with an equal amount of sleep.

* The duration of the sleep deprivation is not directly proportional to the number of hours spent in sleep after the ordeal. In fact, in all three reports about 13 to 15 hours was required, although Gardner had been awake twice as long as the students.

* Even when these volunteers were extremely sleepy, they could not stay asleep for more than 15 hours. There appears to be a limit to how long we can continuously sleep without waking up. Is there a waking centre in the brain?

Momentary sleep whilst the person is apparently still awake is called ‘microsleep’. Microsleep lasts for just a few seconds, but is very refreshing.

Microsleep occurs in less fit people, especially in the elderly. Physical activities tend to reduce the frequency of microsleep. It is well known that when we are older we need less sleep; most elderly people sleep only a few hours each day. Because the elderly have fewer physical activities in the day and are less fit, they lapse into microsleep very frequently during the day. It has been postulated that this is one of the reasons why the elderly do not require that much sleep at night. From the above, we see that the minimum number of hours of sleep can be as little as two hours a day for a short period. We also know that there are no reports of death from insomnia, although there are millions of reports of people who have died from an overdose of the drugs that treat insomnia. So why panic when you cannot sleep for a few hours at night?

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Second, as I have already noted, it is almost always useful when switching from one medication to another to do so gradually, tapering the one while starting the other, overlapping the two medications, which can be used in conjunction in the transition period. Exceptions to this rule are when the medication you are on is causing serious side-effects, in which case you might need to stop it abruptly, or if the two medications are not compatible with each other (about which more below). Even though antidepressants as a group are not addictive and people do not generally experience severe withdrawal on stopping them, abruptly discontinuing them may result in unpleasant symptoms such as interrupted sleep or flu-like feelings. For some people these are worse than for others. For example, a few of my patients have developed the feeling that they are having electric shocks to their body after discontinuing the anti-depressant Seroxat. One factor worth bearing in mind in discontinuing a medication is its half-life. A drug like Prozac, for example, with a long half-life, persists in the system for many days after the drug is discontinued and is far less likely to cause symptoms on withdrawal. The drug Efexor, on the other hand, has a very short half-life, is excreted from the system in a matter of hours rather than days and is far more likely to result in symptoms following withdrawal. In general, withdrawal symptoms are more marked when one discontinues a drug with a shorter as opposed to a longer half-life. In addition to withdrawal symptoms, you risk experiencing a nasty relapse of your depressive symptoms after discontinuing an anti-depressant. In any event, it is generally best to discontinue an anti-depressant medication gradually rather than abruptly. Two anti-depressants may influence each other in ways that are sometimes predictable but often are not. For example, they may enhance each other’s beneficial or adverse effects. For this reason it is often best if they are not co-administered in their full dosage strength.

Say, for example, that you are on Lustral 100 mg per day and want to switch to St John’s Wort 900 mg per day It might make sense to drop to Lustral 50 mg per day while adding 300 mg of St John’s Wort per day for a period of three to four days. After that interval, if there are no ill-effects, one might add another 300 mg of St John’s Wort together with the 50 mg of Lustral for a further four days. At the end of the second week, depending on how you are feeling, it might be reasonable to shift to the full 900 mg of St John’s Wort and stop the Lustral altogether. You might expect some mood instability or side-effects during this transition time because levels of Lustral will be dropping in your blood as levels of St John’s Wort are increasing, but these symptoms should be easily manageable. If they are not, slow down the process. As you can see, it is really best to have a good doctor to guide, accompany and befriend you through this transition process. With Prozac you might want to double the intervals noted above because Prozac has a much longer half-life than Lustral, which means it lingers in the system for longer periods of time.

Other medications might need to be handled somewhat differently depending on the half-lives of the medications and their particular properties.

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