As you know, Benadryl, at around 50-100mgs/night before bed (every 3rd week or so, for that week) will help with keeping your beta-receptors working properly. Beta receptors are embedded in the cell's outer phospholipid membrane. The stability of the membrane has a lot to do with the proper function of the receptors.
Methylation of the phospholipids is stimulated by the binding of beta agonists to their receptors. Methylated phospholipids are foreign to the body, and when the body recognizes tham as foreign, it breaks them down with phospholipase A2. This changes the structure of the outer membrane which results in desensitizaton of the beta receptors. On the other hand, agents that inhibit phospholipase A2 slow desensitization.
Cationic ampiphylic drugs are known for their ability to inhibit phospholipase A2. Benadryl (diphenhydramine) is a cationic ampiphylic drug.
Ergo, Benadryl slows desensitization of Beta receptors (i.e. Upgrades them) by inhibiting phospholipase A2, which is the enzyme that breaks down methylated phospholipids, and this action in turn keeps the phospholipid membrane stable, and thus keeps the receptors functioning properly.
This will allow you to use clen for much longer and it'll still have the same effects. Also, since Benadryl is an anti-histamine, and histamines have a direct effect on beta-adrenoreceptors (not just Beta-2?s but all of them), using an anti-histamine will have a direct effect on reducing beta-receptor stimulation, and thus upregulating your beta-receptors.
In addition, many athletes have issues sleeping while on clen, and Benadryl before bed can help with that.
Finally, stimulants are well known to cause Anxiety in some, and clenbuterol is a stimulant; Benadryl is widely prescribed as an OTC anti-anxiety medication, when people go to emergency rooms with classic panic attack/anxiety symptoms.
SO using benadryl with your clen will upgrade your receptors, help you sleep, and avert stimulant based anxiety.