ECG signal is used for diagnosis of ailments of heart. HRV is used as a predictive and prognostic marker of autonomic dis-functioning. ANS is known to influence heart and any dis-functioning of this system leads to cardiac disorders. ANS has endogenous circadian rhythm. Circadian rhythms are responsible for physical, mental and behavioral changes that follow a roughly 24-hour cycle. Previous studies have shown large inter and intra individual differences in HRV which has lead to difficulties in establishing standard norms. Therefore the aim of our study is to establish a brief protocol for HRV analysis where we will be able to extract features in shorter duration of recording, representative of 24 hour fluctuations in HRV. In this paper we have studied different linear as well as non-linear techniques to analyze circadian HRV. 24 hour ECG recording of 15 subjects using Minimum Activity Protocol subjected for HRV analysis.