Sleep duration individual differences

A. Developmental Changes and Individual Differences in Sleep Duration... 

The extent to which naps will be beneficial, in terms of improved self-perceived alertness, performance, and objective alertness, is likely to depend on a number of factors. The factors of particular significance that will be addressed in this chapter include (a) sleep inertia, (b) nap duration, (c) nap sleep infrastructure, (d) circadian timing, (e) prior wake time, (f) napping strategies for periods of extended wakefulness, (g) individual differences, and (h) the setting (laboratory vs. applied settings). The discussion will now turn to the first of these factors, sleep inertia. 

The vaiious bai biturates differ in the time required for the onset of sleep and in the duration of their effects. All the bai biturates must be used only in strict accordance with instructions to avoid potentially lethal overdoses. Drug dependence in some individuals is also a problem. 

Chronic overdose. Excessive prolonged consumption of caffeine causes anxiety, restlessness, tremors, insomnia headache, cardiac extrasystoles and confusion diarrhoea may occur with coffee and constipation with tea. The cause can easily be overlooked if specific enquiry into habits is not made including children regarding cola drinks. Of coffee drinkers, up to 25% who complain of anxiety may benefit from reduction of caffeine intake. An adult heavy user may be defined as one who takes more than 300 mg caffeine/day, i.e. 4 cups of 150 ml of brewed coffee, each containing 80 20 mg caffeine per cup or 5 cups (60 20) of instant coffee. The equivalent for tea would be 10 cups at approximately 30 mg caffeine per cup and of cola drinks about 2.01. Plainly, caffeine drinks brewed to personal taste of consumer or vendor must have an extremely variable concentration according to source of coffee or tea, amormt used, method and duration of brewing. There is also great individual variation in the effect of coffee both between individuals and sometimes in the same individual at different times of life (see Sleep, above). 

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