Caveolae are nanoscale size invaginations of the plasma membrane identified by their unique flask-shape morphology. They are considered to play an important role in lipid metabolism and provide essential mechanosensing and protective capacity to the membrane. The cytosolic coat composed of the cavin family of proteins, namely Cavin1, Cavin2, Cavin3 and Cavin4, contribute to the formation, stabilisation and function of caveolae. In recent years it has come to light the these cavin proteins participate in several signal pathways within the cell. Caveolae disassembly provoked by mechanical stress or specific signal activation is key to releasing the cavin proteins into the cell to act as signal transducers. These findings led to a new model of caveolae signalling that places the cavin proteins as effectors that associate with intracellular targets. Furthering this model the interactome of cytosolic Cavin3 identified the circadian clock proteins, period 1 (PER2) and cryptochrome 2 (CRY2) which are of immense biological interest due to their intimate role in the circadian rhythm. The circadian clock regulates timing in order to anticipate daily changes in the environment, including light, temperature and food availability for an organisms optimal fitness. The molecular groundwork for these circadian clocks is a transcription-translation feedback loop (TTFL), which takes approximately 24 hrs to complete. In the current model, CLOCK:BMAL1 transcription factors bind to E-box enhancer elements to drive the expression of rhythmically transcribed genes. Among those genes are the canonical repressors PER1-3 and CRY1-2. CRY and PER proteins accumulate in the cytoplasm and after heterodimerization, shuttle into the nucleus to reach a concentration sufficient to block CLOCK:BMAL1 mediated transcription. After the regulated degradation of the PER and CRY proteins, the transcriptional repression phase is relieved and a new cycle can start. Given the importance of PER2 and CRY2 in the molecular clock we investigated the potential role of cavins in the circadian rhythm. We hypothesised cavins serve as modulators of the circadian clock, relaying specific stimuli that disrupt caveolae, to fine tune the circadian rhythm. To test this hypothesis we first characterised the loss of Cavin1 on the circadian rhythm in vivo using the Cavin1 knock out (KO) mouse. We used the traditional circadian cabinets and voluntary running wheel use during free running conditions to discover a small but significant shortening of the locomotor period length. In addition, in the absence of Cavin1 the rhythm of carbohydrate metabolism was perturbed. Lastly a bout of scheduled exercise was used to challenge the free running clock and this demonstrated a differential phase shift response from the Cavin1 KO mouse. The in vivo characterisation provided strong evidence of the role of Cavin1 in the circadian rhythm and we therefore transitioned into cellular models to further interrogate this system. Through mRNA quantitation of clock controlled genes we demonstrated that loss of Cavin1 or Cavin3 leads to several changes in clock gene expression. Most noticeably, the downregulation of Per2 and Dbp mRNA. We followed this up a more specific look at the dynamics of the negative limb components CRY1 and PER2. Live nuclear monitoring of endogenous CRY1, in cells overexpressing Cavin1 or Cavin3, over several days revealed a severely dampened protein oscillation. Study of PER2 protein in cells revealed that both Cavin1 and Cavin3 negatively regulate its stability. Our findings suggest that both Cavin1 and Cavin3 are required for stable CRY1 oscillation and PER2 accumulation and thus the function of the repressive phase of the molecular clock. Finally we addressed the nature of the cavin-PER2 interaction and then explored potential regulatory mechanisms, with a focus on caveola disassembly. Through the use of pulldown assays and in vitro protein expression and subsequent interaction analysis we were able to establish that both the HR1 domain of Cavin1 and Cavin3 directly interacts with PER2. In support of our hypothesis caveolae disassembly stimulated by oxidative stress led to an upregulated interaction between Cavin1 and Cavin3 with PER2. This presents a novel pathway by which the molecular clock senses the cells redox state. The ubiquitous core clock machinery in contrast to the tissue specific expression of cavins narrowed our focus to cavins regulating peripheral muscle clocks. Per2 gene expression is responsive to in vivo and in vitro contraction of skeletal muscles through a calcium (Ca2+) dependent pathway. Given the high density of caveolae on muscle membranes we explored the idea that contraction and/or Ca2+ signals the core clock through cavin proteins. Increasing intracellular Ca2+ through a short bout of ionomycin treatment released Cavin1 and Cavin3 from the membrane with a concurrent loss of caveolae density at the membrane. Functionally, this led to an increase in the Cavin1-PER2 interaction and thus we present a new and unique pathway in which Ca2+ acts on the molecular clock. Overall the work performed in this thesis has made a significant contribution towards understanding the role of caveolae and cavins in the circadian rhythm and additionally further expands our current knowledge of cavins in health and disease.