How do organisms cope with stressful external environmental conditions which are localised or of short duration.

If an organism cannot survive in a particularly stressful external environmental condition then it will undergo hibernation and aestivation which are the periods of dormancy. In the dormant condition, the organism will lower its needs.

And when the conditions are really sustainable and favourable for the organism, the dormant condition will have an end. In case of animals hibernation is the winter sleep and aestivation is the summer sleep by which they escape the external conditions