Alisha U:

Some people might try to regulate their bodies too much like taking pills to sleep then different pills in the morning to wake up. when any drug is used consistently immunity, the addiction is built up, so a person may feel the need to take both kinds of pills/drugs despite whether they feel effects or not.

Mathieu:

The other answers are somewhat wrong.

Firstly the term “depressant” is not a good term to use. It leads to confusion about how the drugs work and what type of drug it is. Stimulant is an OK term but some people think of amphetamine/cocaine when the hear “stimulants”.

Also caffeine does not cause addiction. That is simply a fact. Medically there are two diagnoses used “substance abuse” which is drug abuse but not an actual addiction and “substance dependency” which is addiction. There is no diagnosis of caffeine abuse or dependency, it simply does not exist. Physical dependency (which is NOT addiction) does typically occur when large amounts of caffeine are used continuously. However that simply means that the body has physically adapted to having the substance and if the caffeine is stopped some mild physical withdrawal can occur.

People may say caffeine is addictive but technically under medical guidelines and diagnostic criteria it is not.

“Sleeping pills” is also not specific. There are many types of sleeping pills and many are NOT addictive. It is a common misconception because many sleeping pills are addictive and in the past they have all been addictive.

For example some over the counter antihistamines like Benadryl (diphenhydramine) and Unisom (doxylamine) are used for sleep but they are not addictive. Also some prescription antihistamines, most commonly Vistaril/Atarax (hydroxyzine) is sometimes used and it is NOT addictive.

It has also become popular to use low doses of sedating antidepressants like Desyrel (trazodone), Remeron (mirtazapine), and Elavil (amitriptyline). In fact most of the five most prescribed “sleeping pills” in The US are antidepressants. Only two of the five most prescribed are addictive (Ambien, Lunesta). Even drugs like Seroquel (quetiapine), an atypical antipsychotic, are used for sleep. Unfortunately none of these drugs are approved for insomnia, there are no significant studies that show they are effective, they have very serious risks associated with them, and medical organizations including The American Academy of Sleep Medicine and The American Family Physician indicate they should not be used in most situations.

However the drug Rozerem (ramelteon) is approved for sleep, it has some clinical evidence it works, and it is not addictive.

The addictive hypnotics (typically “hypnotics” refer to the drugs that are potentially addictive) are very rarely abused and when they are abused it is typically by people with other addictions (heroin, amphetamine, cocaine, alcohol). Also most addicts will do extreme dose escalation without doctor approval so they may be taking many times more medicine then they should.

However looking at addiction and thinking of stimulants and “depressants” and opposites is not exactly correct. What makes things addictive is dopamine. All addictive drugs release the neurotransmitter dopamine and that causes pleasure and it reinforces behaviour. Anytime you do something fun, something you enjoy, there is an increase in dopamine so you keep liking it and keep doing it. Addiction is when there is a problem in the reward pathway in the brain and people then start to lose control, they crave the drug, and psychologically “need it” thus addiction is a psychological dependency.

So it is not odd for people to be addicted to stimulants and depressants. Some people take amphetamines in the morning “get them going” and then take hypnotics to make them sleep.

More than half of all cocaine addicts are also alcoholics. Often they will use cocaine to stay awake to then drink, then they use more cocaine to get higher and to counteract the sedating aspect of alcohol, and that pattern can go on for hours.

But in your example of caffeine and sleeping pills there can’t be true addiction to caffeine at all.

Here is a list of addictive hypnotics (not all are available in all countries):
Ambien, Stilnox (zolpidem)
Ambien CR (zolpidem extended-release)
Edluar (zolpidem sublingual)
Sonata (zaleplon)
Imovane/Zimovane (zopiclone)
Lunesta (eszopiclone)
Doral (quazepam)
Restoril/Euhypnos/Normison (temazpam)
Halcion (triazolam)
Lectopam, Lexotan (bromazepam)
Mogadon (nitrazepam)
Dormonoct (loprazolam)
Dalmane (flurazepam)
ProSom (estazolam) 
Rohypnol (flunitrazepam)
Hypnovel (midazolam)
Seconal (secobarbital)
Butisol (butabarbital)
Amytal (amobarbital)
Nembutal (pentobarbital)
Tuinal (amobarbital/secobarbital)
Mebaral (mephobarbital)
Luminal (phenobarbital)
Somnote, Aquachloral Supprettes (chloral hydrate)
Placidyl (ethchlorvynol)
Carbrital (pentobarbital and carbromal)