Evaluation

• Strength-improved understanding of age-related changes in sleep. it has been observed that SWS reduces with age. growth hormone is mostly produced during SWS, therefore reduced in elders. Cauter et al (2000) concluded the resulting sleep deficit may explain various issues in old age. eg. reduced alertness. Relaxation and meditation is likely to increase SWS. this suggests that this knowledge of ultradian rhythms has practical value.
• Individual differences - x - There is significant variation between people. Tucker et al (2007) found large differences between participants in terms of the duration of each sleep stage particularly in stage 3 and 4. Tucker suggested these are biologically determined which makes it difficult to describe normal sleep.
• The sleep lab - Conducting sleep studies in lab settings can help control extraneous variables, therefore, researcher can exclude temporary variables such as noise/temp which may affect sleep. Lab studies involve being attached to complicated machinery leading to participants to sleep in a way which does not represent their ordinary sleep patterns.