AIt is estimated that one in three adults in westernised countries regularly wakes up in the middle of the night and has difficulty getting back to sleep. Physicians often diagnose 'insomnia' and prescribe sleeping pills, but these often have side.effects such as negative interactions with food, drink or other drugs, and most are habit-forming. Cessation of the medication frequently causes unpleasant with drawal symptoms, too, including panic attacks mood-swings,and even heightened sleep disturbance. Is there a way to treat insomnia without such debilitating consequences?

BThe historian A. Roger Ekirch takes a different approach to nocturnal awakening. He maintains it is biologically instinctive and innate and that it is the ideal of the modern-era condensed eight-hour sleep regime that is exceptional. Those people who have so-called insomnia may just be sleeping in the biphasic mode that was the norm for their ancestors: eight hours of sleep split into two chunks by a period of wakefulness which lasted an hour or longer. According to Ekirch, during this sleepless phase, some people might have stayed in bed and prayed, recalled their dreams, or chatted to their partners, while others may have got up to do chores or drop in on the people next door.

CArchives from the pre-industrial era mentionsegmented sleep as 'first sleep' or 'deep sleep' and 'second sleep' or 'morning sleep'. The change in sleep routines, which started during the Industrial Revolution, mainly came about through the invention of the incandescent bulb. This invention, cheap and available to even the poorest residences, lengthened our daytime activities, such as reading and playing games, and reduced the period of time for sleep. As a result, the modern worker or student tries to squeeze sleep into a continuous period of seven or eight hours, even though this does not conform to natural circadian rhythms. Anthropologists confirm Ekirch's hypothesis by reporting that inhabitants of Undeveloped regions of the world that are without the benefit of electric lighting still follow the natural rhythm of a divided sleep pattern.

DEkirch's hypothesis was corroborated by sleep expert Thomas Wehr in the 1990s. His study kept volunteers in the dark for 14 hours each night (a simulation of winter time exposure to light and darkness in bygone days). The subjects moved progressively towards a biphasic sleep pattern, taking a couple of hours to doze off and then sleeping in two distinct segments of four hours each with an interval of wakefulness in the middle. He construed from this that bifurcated sleep is not only completely natural but also beneficial, because this kind of sleeping facilitates the recall of dreams, which 'afford people a pathway to their subconscious'. Our predecessors actually considered their dream life to be a crucial component of their lives.

ESleep is essential and it is by no means a passive state. Sleep scientists have revealed that there are two fundamental cycles of activity, classified as rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. The latter consists of four phases. The first phase, which lasts five to ten minutes, is the 'falling asleep' stage and sometimes there is actually a sense of falling, which often causes a sudden muscle contraction or jerk. One is easily awoken during this stage. Then comes an interlude of light sleep where the heart rate slows and body temperature drops - the body is getting ready for the deep sleep, which often causes a sudden muscle contraction or jerk. One is easily awoken during this stage. Then comes an interlude of light sleep where the heart rate slows and body temperature drops - the body is getting ready for the deep sleep, which occurs in the third and fourth stages of NREM slumber. This is slow-wave or 'delta' sleep, and a person woken at this stage may feel quite disorientated. This period of deep sleep is vital for the body to restore itself. During this time, not only does the body carry out repair and regeneration of nerves, bones and muscles, but it also fortifies and repairs the immune system.

FThe eyes can be seen to move rapidly beneath the eyelids during REM sleep, which ensues after approximately an hour and a half of NREM sleep cycles. A faster and more erratic heart rate and shallow breathing are typical of this state, and brain activity intensifies, giving rise to vivid dreaming; paradoxically, the major voluntary muscle groups are immobilised, albeit for good reason - thrashing about while asleep could result in serious injury. Although the purpose of dreaming is not yet fully comprehended, the hypothesis is that it is vital for learning and memory (as these regions of the brain are stimulated); indeed, studies have shown that when candidates are denied REM sleep, their memory of recent learning is impaired. Deprivation of REM sleep also leads to anxiety and migraine headaches.

GSleep specialists agree that without adequate REM and NREM sleep, people's thought processes are likely to be compromised, and they may suffer from impaired memory, fatigue, depression, a weakened immune response, and heightened susceptibility to pain, amongst other negative consequences. Yet modern-day humans remain chronically sleep deprived, notwithstanding the results of this research and its acceptance by many psychiatrists and sleep consultants. Why is the general populace so loath to relinquish its monophasic sleep schedule and enjoy the benefits of a biphasic schedule? It is certain that attitudes to employment responsibilities and social commitments would have to be altered before such a huge behavioural paradigm shift could occur and individuals could allot more time to restful, restorative sleep.