Peptide hydrogels are excellent candidates for medical therapeutics due to their
tuneable viscoelastic properties, however, in vivo they will be subject to various osmotic pressures, temperature changes and biological cosolutes which could alter their performance. Peptide hydrogels formed from the synthetic peptide I3K have a temperature induced hardening of their shear modulus by a factor of 2. We show that the addition of uncross-linked poly(N-isopropylacrylamide) (pNIPAM) chains to the peptide gels increases the gels' temperature sensitivity by 3 orders of magnitude through the control of osmotic swelling and cross-linking. Using machine learning combined with single-molecule fluorescence microscopy we measured the modulation of states of pre-stress in the gels on the level of single peptide fibres. A new self-consistent mixture model was developed to simultaneously quantify the energy and the length distributions of the states of pre-stress. Switching the temperature from 20C to 40C causes six fold increases in the number of states of pre-stress. At the higher temperature many of the fibres experience constrained buckling with characteristic small wavelength oscillations in their curvature.