You may have heard of sleep tapes that offer effortless learning during sleep. Your investment in such tapes will not be money well spent. Learning during sleep should be discouraged! It is possible to occasionally recall a fraction of the material presented during sleep (probably only then when it enters your brain during short periods of transition from REM to temporary waking). There is also ample evidence that some circuits in the brain can be conditioned during REM sleep; however, the connection between the senses and the brain in sleep is rather focused on awakening in danger rather than on processing complex information.

Whatever you might gain from your sleep tapes will by far be offset by damage to the quality of sleep. If the learning stimuli do not reach a certain threshold, they will simply be ignored. However, past a certain value they may prevent the progression of NREM sleep toward stages 3 and 4. They can also shorten REM sleep.

Interestingly, memories acquired minutes before falling asleep do not get consolidated! Even a few minutes of sleep leave a short window of waking time with a complete memory erasure. Luckily, we rarely learn mission-critical information shortly before dozing off.

Counter-recommendation for learning during sleep, does not imply that falling asleep with TV or radio turned on should be discouraged. If you would like to get a dose of education yet before falling asleep, be sure your tapes, TV or radio meet these conditions:

· they turn off automatically no later than in 30 minutes

· they have no ability to wake you up from a properly timed sleep. If you wake up from initial minutes of sleep you may experience a dramatic shift in the homeostatic component that would delay the sleep onset (awakening may also indicate that you went to sleep too early in reference to your circadian cycle)

· they do not include highly emotional content, distressing messages, shrill sounds (doorbells, phones, timers and alarm clocks; these have all been designed to produce sounds that tend to most effectively rouse the central nervous system)

TV, radio or tapes in the morning are OK too, on condition you turn them on manually (i.e. they should not work as an alarm clock substitute). If you wake up slightly ahead of your expected waking time, turn on the news and stay in bed. Test your brain for signs of sleepiness. Occasionally, you may still be able to fall asleep and go through one cycle of sleep that will be beneficial to your intellectual performance. Be sure that this does not become a routine, esp. if you are awakened early due to the pressure in the bladder[3]. Unless your urologist recommends otherwise, you should avoid drinking water and other liquids 2-3 hours before going to sleep