Crested Gecko Lighting: UVB and Heat Requirements

Crested geckos (Correlophus ciliatus) are nocturnal, arboreal lizards native to New Caledonia. Their lighting and heating needs differ substantially from those of diurnal desert reptiles, and incorrect setups are a common cause of poor health in captivity. This article explains the current evidence on UVB provision, gives practical lighting schedules, lists suitable bulb types with safe mounting distances, and describes how to monitor and adjust your setup. The guidance is written for owners, veterinary students, veterinary technicians, and veterinary professionals who need a clear framework for evaluating crested gecko lighting and heating.

The direct answer to the most common question is this: crested geckos do not require intense basking heat or high-output UVB lighting to survive, but they do benefit from low-level UVB exposure and a defined photoperiod that mimics their natural tropical habitat. Heat should be provided gently and never allowed to exceed safe limits. The sections below explain the reasoning, the equipment choices, and the management steps that translate this principle into a reliable daily routine.

At a Glance: Crested Gecko Lighting and Heating Summary

Why Crested Gecko Lighting Is Different From Other Reptiles

Crested geckos occupy a specific ecological niche that shapes their captive care requirements. They are nocturnal and arboreal, spending daylight hours hidden in dense vegetation and emerging at night to forage. Their natural habitat in New Caledonia is a tropical forest with moderate temperatures and high humidity. This background matters because many reptile lighting recommendations are developed for diurnal desert species such as bearded dragons or blue-tongued skinks, which bask in intense sunlight for much of the day. Applying those same standards to crested geckos can cause overheating, dehydration, and chronic stress.

The Merck Veterinary Manual provides general guidance on reptile husbandry and emphasizes that appropriate environmental conditions are foundational to preventive health care. The World Organisation for Animal Health similarly frames animal welfare as dependent on meeting species-specific behavioral and physiological needs. For crested geckos, this means providing a thermal gradient and a light cycle that respect their nocturnal activity pattern instead of forcing them into a diurnal schedule.

A common misconception is that crested geckos need no lighting at all because they are active at night. This view overlooks two important facts. First, all reptiles benefit from a consistent light-dark cycle to regulate circadian rhythms, activity, feeding, and reproduction. Second, crested geckos in the wild may be exposed to indirect or filtered UVB during dawn and dusk periods when they move through the canopy. The question is not whether to provide light, but how much and of what type.

The UVB Debate: What the Evidence Shows

The role of UVB in crested gecko health is a subject of ongoing discussion among keepers and veterinarians. UVB radiation enables reptiles to synthesize vitamin D3 in the skin, which is then used to regulate calcium metabolism. Without adequate vitamin D3, reptiles can develop metabolic bone disease, characterized by weak bones, muscle tremors, and poor appetite. The debate centers on whether crested geckos, as nocturnal animals, require UVB at all, or whether dietary vitamin D3 supplementation is sufficient.

Direct studies on crested geckos are limited, but research on related lizard species provides useful context. A 2025 study on blue-tongued skinks (Tiliqua scincoides) investigated the effect of UVB exposure on plasma 25-hydroxyvitamin D concentrations. Eleven adult skinks were exposed to either 12 hours or 2 hours of UVB per day for four weeks. Plasma 25-OHD concentrations were very low at baseline and increased significantly in both groups after UVB exposure. The 12-hour group rose from a baseline of 18.5 nmol/L to 820 nmol/L, while the 2-hour group rose from 22 nmol/L to 635 nmol/L. After UVB was discontinued, 25-OHD concentrations gradually declined and returned to baseline at 7 months in the 12-hour group and 4 months in the 2-hour group. The study also found that dietary vitamin D3 provided through wet cat food alone was insufficient to sustain plasma 25-OHD concentrations. The authors concluded that blue-tongued skinks rely on UVB exposure to increase their 25-OHD concentrations, and that the shorter 2-hour exposure provided a significant rise while potentially reducing secondary risks associated with UVB exposure. See the full study at Measuring the Rise and Fall of Plasma 25-Hydroxyvitamin D Concentrations in Blue-Tongued Skinks Following Ultraviolet B Exposure and Withdrawal.

This study is not about crested geckos, and the results should not be transferred directly across species. However, it demonstrates two principles that apply to crested gecko care. First, even a relatively short daily UVB exposure can produce a meaningful increase in vitamin D status. Second, UVB withdrawal leads to a gradual decline in vitamin D, meaning that intermittent or inconsistent UVB provision may not maintain adequate levels over time.

For crested geckos, a conservative approach is to provide low-level UVB for a portion of the day. This mimics the filtered light they might encounter in the wild and supports vitamin D synthesis without forcing the animal into prolonged bright conditions. A 2% to 5% UVB fluorescent tube mounted at the manufacturer's recommended distance is appropriate. The bulb should be placed over a branch or foliage area where the gecko can choose to sit, not over the entire enclosure. This allows the gecko to self-regulate its exposure, which is consistent with the behavioral thermoregulation observed in nocturnal lizards.

A 2019 study of a tropical nocturnal gecko, the Australian house gecko (Gehyra dubia), found that these animals actively seek warm microclimates at night to maintain body temperatures warmer than most available environmental temperatures. The study showed that nocturnal geckos can be highly effective thermoregulators when appropriate thermal heterogeneity exists in their environment. See Heat seekers: A tropical nocturnal lizard uses behavioral thermoregulation to exploit rare microclimates at night. This finding supports the practice of providing temperature gradients and choice points in crested gecko enclosures, even though the species is nocturnal.

Heat Requirements: Gentle Warmth, Not Intense Basking

Crested geckos are adapted to moderate tropical temperatures and do not require the intense basking spots needed by desert reptiles. The optimal temperature range for crested geckos is 22 to 26 °C (72 to 79 °F) during the day, with a nighttime drop to 18 to 22 °C (65 to 72 °F). Temperatures above 28 °C (82 °F) for extended periods can cause heat stress, dehydration, and death. Temperatures below 15 °C (59 °F) can suppress appetite and immune function.

The thermal environment should include a gradient so the gecko can move between warmer and cooler areas. In a vertical enclosure, which is preferred for arboreal species, the top of the enclosure will naturally be warmer than the bottom. A low-wattage ceramic heat emitter or a heat mat attached to the side or back of the enclosure can create a gentle warm zone. All heat sources must be connected to a thermostat to prevent overheating. Hot rocks and unguarded incandescent bulbs are unsafe and should never be used.

The importance of temperature control extends beyond comfort. Reptiles are ectothermic, meaning their body temperature depends on the environment. Digestion, immune function, and activity all depend on maintaining appropriate body temperatures. A 2026 case report on anesthesia in an Argentine black and white tegu (Salvator merianae) highlighted the importance of active thermal management during veterinary procedures, noting that temperature control was essential for maintaining physiologic stability. See Case Report: Anesthesia for cloacal prolapse fixation surgery in an Argentine black and white tegu. While this report concerns a different species and a surgical context, it reinforces the general principle that temperature is a critical variable in reptile health.

For crested geckos, the practical implication is that a thermometer should be placed at both the warm and cool ends of the enclosure, and temperatures should be checked daily. A digital thermometer with a probe is more accurate than a stick-on analog thermometer. If the enclosure is in a room that stays within the target range, additional heating may not be needed. If the room is cooler, a low-wattage heat source with a thermostat can maintain the gradient.

Lighting Schedules: Photoperiod and Daily Rhythm

A consistent light-dark cycle is essential for crested gecko health. In the wild, crested geckos experience roughly 12 hours of daylight and 12 hours of darkness, with seasonal variation. In captivity, a 10 to 12 hour photoperiod is appropriate year round. A timer should be used to turn lights on and off at the same time each day. This consistency supports normal circadian rhythms, feeding behavior, and activity patterns.

The light source for the photoperiod does not need to be a UVB bulb. A low-wattage LED or fluorescent light can provide illumination for the enclosure and support live plants if they are used. The UVB bulb, if used, can be on the same timer or on a separate timer for a shorter duration. Some keepers prefer to run the UVB bulb for only 2 to 4 hours in the morning, while others run it for the full photoperiod. The evidence from the blue-tongued skink study suggests that even 2 hours of UVB per day can produce a significant rise in vitamin D concentrations, so a shorter UVB period is a reasonable choice for crested geckos. See Measuring the Rise and Fall of Plasma 25-Hydroxyvitamin D Concentrations in Blue-Tongued Skinks Following Ultraviolet B Exposure and Withdrawal.

The photoperiod also affects behavior. Crested geckos are most active at dawn and dusk, and they may be reluctant to emerge during bright daylight. Providing dense foliage and hiding spots allows the gecko to choose when to be exposed to light. A well-planted enclosure with branches, vines, and leafy cover creates a sense of security and encourages natural behavior.

Seasonal variation in photoperiod can be introduced to mimic natural cycles, but this is not required for basic maintenance. If breeding is intended, a slight reduction in day length during the cooler months followed by a gradual increase can stimulate reproductive behavior. For most owners, a consistent 10 to 12 hour photoperiod is sufficient.

Choosing UVB Bulbs: Types, Output, and Mounting Distance

Several types of UVB bulbs are available for reptile enclosures. The main categories are compact fluorescent bulbs, linear fluorescent tubes (T5 and T8), and mercury vapor bulbs. For crested geckos, low-output fluorescent bulbs are the safest choice. Mercury vapor bulbs produce intense heat and UVB and are not appropriate for this species.

Compact fluorescent bulbs are screw-in bulbs that can be used in a standard dome fixture. They are available in 2%, 5%, and 10% UVB outputs. For crested geckos, a 2% or 5% bulb is appropriate. The bulb should be mounted at the distance specified by the manufacturer, typically 20 to 30 cm (8 to 12 inches) from the basking area. Because compact bulbs produce a narrow beam of UVB, they are best used over a specific basking spot instead of for whole-enclosure coverage.

Linear fluorescent tubes provide broader coverage and are generally preferred for larger enclosures. T5 tubes are more efficient and produce higher output than T8 tubes. A 2% or 5% T5 tube mounted at the manufacturer's recommended distance is suitable for crested geckos. The tube should be placed along the top of the enclosure, with the basking branch positioned below it at the correct distance.

The mounting distance is critical because UVB output decreases rapidly with distance. A bulb mounted too far away provides little or no benefit, while a bulb mounted too close can cause eye damage or skin burns. Mesh screens can block a significant portion of UVB, so the distance should be measured from the bulb to the gecko's basking spot, accounting for any screening. The manufacturer's instructions should always be followed.

UVB bulbs degrade over time, even if they continue to produce visible light. Most fluorescent UVB bulbs should be replaced every 6 to 12 months, depending on the manufacturer's recommendation. A UVB meter can be used to measure output, but these meters are expensive and not necessary for most owners. Marking the replacement date on the bulb or on a calendar is a simple way to track bulb age.

Setting Up the Enclosure: Practical Steps

The enclosure setup should be planned before the gecko is introduced. A vertical enclosure is preferred because crested geckos are arboreal and will use height more than floor space. A minimum size for a single adult is 45 by 45 by 60 cm (18 by 18 by 24 inches), with larger enclosures providing more enrichment.

The following steps outline a practical approach to setting up lighting and heating:

1. Place the enclosure in a room that stays within the target temperature range, away from direct sunlight, drafts, and heating or cooling vents.
2. Install a thermometer at the warm end and another at the cool end. Digital thermometers with probes are recommended.
3. Install the heat source on one side of the enclosure, connected to a thermostat. Set the thermostat to maintain the warm end at 24 to 26 °C (75 to 79 °F) during the day.
4. Install the UVB bulb along the top of the enclosure, positioned over a branch or foliage area. Follow the manufacturer's instructions for mounting distance.
5. Connect the UVB bulb and any general lighting to a timer set for 10 to 12 hours of light per day.
6. Add branches, vines, and dense foliage to create vertical climbing opportunities and hiding spots. The gecko should be able to move between shaded and lit areas.
7. Monitor temperatures for several days before introducing the gecko. Adjust the thermostat or bulb position as needed to achieve the target gradient.
8. Keep a daily log of temperatures, bulb status, and gecko behavior for the first few weeks.

This setup allows the gecko to choose its preferred temperature and light exposure. The warm end provides a gentle heat source, while the cool end offers a retreat. The UVB bulb is positioned so the gecko can bask if it chooses, but it is not forced into bright light.

Bulb Comparison Table

The table above provides general guidance. Always follow the manufacturer's instructions for the specific bulb you purchase, as output and recommended distances vary between brands.

Monitoring and Records: What to Track

Consistent monitoring is the foundation of good reptile husbandry. A simple record-keeping system helps identify problems early and provides useful information for veterinary consultations. The following items should be recorded daily or weekly:

Daily temperature readings at the warm and cool ends of the enclosure. Record both daytime and nighttime temperatures. Note any deviations from the target range and any adjustments made to the thermostat or heat source.

UVB bulb status, including the installation date and the expected replacement date. Note any visible changes in bulb output or flickering.

Gecko behavior, including activity level, time of emergence, appetite, and stool frequency. Changes in behavior can be the first sign of health problems.

Feeding records, including what was offered, how much was eaten, and any supplements used. Crested geckos are omnivorous and benefit from a varied diet of commercial crested gecko diet, insects, and occasional fruit.

Shedding events and any signs of difficulty shedding, such as retained skin on the toes or tail.

Weight measurements taken monthly. A digital kitchen scale accurate to 1 gram is suitable. Weight loss is a serious concern and warrants veterinary attention.

These records do not need to be elaborate. A notebook or a spreadsheet with columns for date, temperature, behavior, feeding, and notes is sufficient. The act of recording forces regular observation and creates a baseline against which changes can be measured.

Common Failure Patterns in Lighting and Heating

Several recurring mistakes lead to health problems in crested geckos. Recognizing these patterns can prevent illness and reduce the need for veterinary intervention.

The first pattern is overheating. Owners who apply desert reptile standards to crested geckos may provide a basking lamp that raises the enclosure temperature above 28 °C (82 °F). Signs of overheating include lethargy, gaping, seeking the coolest part of the enclosure, and reduced appetite. Prolonged overheating can be fatal. The solution is to remove high-output heat sources and rely on low-wattage heating with a thermostat.

The second pattern is insufficient heat. Enclosures kept in cool rooms without supplemental heating can drop below 18 °C (65 °F), especially at night. Chronic cool temperatures suppress digestion and immune function, leading to weight loss, regurgitation, and respiratory infections. A low-wattage ceramic heat emitter with a thermostat can maintain the nighttime temperature within the target range.

The third pattern is incorrect UVB mounting. A UVB bulb mounted too far from the basking area provides no measurable benefit, while a bulb mounted too close can cause eye irritation, squinting, and skin burns. Owners should measure the distance from the bulb to the basking branch and adjust according to the manufacturer's instructions.

The fourth pattern is inconsistent photoperiod. Lights left on 24 hours a day or turned on and off at irregular times disrupt circadian rhythms and can cause chronic stress. A timer set to a consistent 10 to 12 hour schedule resolves this issue.

The fifth pattern is reliance on dietary vitamin D3 alone without UVB. While commercial crested gecko diets are supplemented with vitamin D3, the blue-tongued skink study found that dietary vitamin D3 alone was insufficient to sustain plasma 25-OHD concentrations. See Measuring the Rise and Fall of Plasma 25-Hydroxyvitamin D Concentrations in Blue-Tongued Skinks Following Ultraviolet B Exposure and Withdrawal. Providing low-level UVB in addition to a supplemented diet is a more robust approach.

The sixth pattern is ignoring seasonal temperature variation. Some owners keep the enclosure at the same temperature year round, which may not match the gecko's natural seasonal cycle. A slight reduction in temperature during the cooler months, followed by a gradual increase, can support normal physiological rhythms.

Welfare and Safety Context

Reptile keeping carries welfare responsibilities that extend beyond basic survival. The World Organisation for Animal Health defines animal welfare as the state of the animal in relation to its environment, and it emphasizes that welfare is compromised when animals cannot express normal behavior or when their physiological needs are not met. For crested geckos, this means providing an environment that allows climbing, hiding, thermoregulation, and natural activity patterns.

A 2023 study of reptile keepers in Brazil found that many keepers spent less than US$30 per month on their reptiles and kept them in enclosures with basic environmental complexity. The study noted that reptiles are often associated with an incorrect belief that they are simple and easy to keep compared with dogs and cats, but that keeping reptiles can pose several challenges in meeting their needs in a domestic setting. See Keeping reptiles as pets in Brazil: keepers' motivations and husbandry practices. This finding applies to lighting and heating as well as to other aspects of care. A minimal setup that provides only the bare essentials may keep a crested gecko alive, but it may not support good welfare.

The Health and Welfare of Captive Reptiles, Second Edition is a relevant reference for veterinary professionals seeking a deeper understanding of reptile welfare science. Similarly, A study of animal welfare in 11 species across 16 Zoos using M-AWAG and its correlations with environmental variables provides a framework for assessing welfare across species. These references support the principle that environmental complexity and appropriate lighting are components of welfare, not optional extras.

Safety considerations apply to both the animal and the owner. Electrical equipment must be installed according to the manufacturer's instructions, with all connections protected from moisture. Heat sources must be secured so they cannot fall into the enclosure. Thermostats should be tested regularly to ensure they are functioning correctly. Owners should be aware that UVB bulbs emit radiation that can be harmful to human eyes and skin, and they should not look directly at an operating bulb.

Limitations of Current Evidence

The evidence base for crested gecko lighting is limited. Direct studies on UVB requirements in crested geckos are lacking, and recommendations are often extrapolated from research on other lizard species. The blue-tongued skink study provides useful data on UVB and vitamin D dynamics, but the species differs from crested geckos in ecology, diet, and natural history. See Measuring the Rise and Fall of Plasma 25-Hydroxyvitamin D Concentrations in Blue-Tongued Skinks Following Ultraviolet B Exposure and Withdrawal. Similarly, the study of nocturnal thermoregulation in Australian house geckos demonstrates that nocturnal lizards can thermoregulate effectively, but it does not directly address crested gecko husbandry. See Heat seekers: A tropical nocturnal lizard uses behavioral thermoregulation to exploit rare microclimates at night.

Veterinary professionals should be aware of these limitations when advising clients. Recommendations should be presented as evidence-informed guidance instead of definitive protocols. Owners should be encouraged to observe their geckos closely and adjust the setup based on individual responses.

The Merck Veterinary Manual is a useful reference for general reptile medicine, and the World Organisation for Animal Health provides a framework for welfare assessment. Neither source provides species-specific lighting protocols for crested geckos, which underscores the need for careful observation and conservative management.

Professional Escalation Criteria

Most lighting and heating issues can be resolved by adjusting the setup, but some situations require veterinary attention. Owners should seek veterinary care if they observe any of the following:

Weight loss despite normal appetite, or a decrease in appetite lasting more than one week.

Lethargy, weakness, or reduced activity for more than two days.

Difficulty shedding, especially retained skin on the toes, tail, or around the eyes.

Swollen limbs, jaw deformities, or muscle tremors, which may indicate metabolic bone disease.

Eye problems, including squinting, discharge, or swelling.

Burns or skin lesions, which may result from incorrect heat source placement.

Respiratory signs, including open-mouth breathing, wheezing, or nasal discharge.

Any sudden change in behavior or appearance.

Veterinary professionals should take a thorough history, including the lighting and heating setup, bulb type and age, mounting distance, photoperiod, and temperature records. This information is essential for diagnosing environmental causes of illness. The Merck Veterinary Manual provides guidance on reptile examination and diagnostic approaches.

For veterinary professionals managing reptile cases, the Health and Welfare of Captive Reptiles, Second Edition is a relevant reference. The case report on anesthesia in a tegu lizard also illustrates the importance of thermal management during veterinary procedures, which is relevant when reptiles are anesthetized for any reason. See Case Report: Anesthesia for cloacal prolapse fixation surgery in an Argentine black and white tegu.

A Practical Decision Framework for Crested Gecko Lighting Adjustments

Selecting the correct lighting and heating setup is only the first step in crested gecko management. The more important skill is knowing when and how to adjust the setup based on observed behavior, physical condition, and environmental measurements. This section provides a structured decision framework that owners and veterinary professionals can use to evaluate whether a lighting or heating change is needed, what change to make, and when to escalate to professional care.

Step 1: Establish a Baseline With a Weekly Observation Score

Before making any adjustments, record a baseline for each gecko. A simple scoring system applied once per week at the same time of day provides a consistent reference point. Score each category from 1 to 5, where 1 indicates a serious concern and 5 indicates normal function.

A total score below 15 out of 25 warrants a review of the lighting and heating setup before considering other causes. A score below 10 warrants veterinary consultation. This scoring system is not a diagnostic tool, but it creates a repeatable record that helps distinguish temporary variation from a developing problem.

Step 2: Measure Before You Adjust

Do not change bulbs, distances, or timers based on guesswork. Take three measurements first: the warm end temperature, the cool end temperature, and the distance from the UVB bulb to the highest basking branch. Record these values in the daily log. Digital thermometers with probes are more reliable than stick-on analog models, which can be inaccurate by several degrees.

For the UVB distance, measure from the bulb surface to the branch surface, not from the top of the enclosure. If a mesh screen sits between the bulb and the branch, measure from the bulb to the branch and note the screen type. Fine metal mesh can block a substantial portion of UVB output, so a bulb that was adequate without screening may need to be mounted closer or replaced with a higher-output model when screening is present.

Step 3: Apply the Adjustment Decision Tree

Use the following decision tree to determine whether a change is needed and what change to make. Each branch addresses a specific observation pattern.

Branch A: Low activity and poor appetite with normal temperatures

If temperatures are within the target ranges but the gecko is lethargic and eating poorly, check the photoperiod first. Lights left on for more than 14 hours per day can disrupt circadian rhythms. Reduce the photoperiod to 10 to 12 hours using a timer. If the gecko does not improve within 7 days, check the UVB bulb age. A bulb older than 12 months may produce visible light but little UVB. Replace the bulb and record the installation date.

Branch B: Gecko avoids the warm end and stays at the cool end

This pattern suggests the warm end is too hot. Measure the warm end temperature with a digital probe. If it exceeds 28 °C (82 °F), reduce the thermostat setting by 1 to 2 degrees and recheck after 24 hours. If the warm end is within range but the gecko still avoids it, the heat source may emit visible light that discourages the gecko from approaching. Switch to a ceramic heat emitter, which produces heat without light.

Branch C: Gecko spends excessive time under the UVB bulb

A gecko that sits directly under the UVB bulb for most of the day may be seeking warmth instead of UVB. Check the temperature at the basking branch. If it is below 24 °C (75 °F), the gecko may be using the bulb as a heat source. Provide a separate low-wattage heat source at the basking branch and observe whether the gecko shifts its position. If the gecko continues to sit under the UVB bulb despite adequate warmth, the bulb may be too dim or mounted too far away, and the gecko is not receiving a meaningful UVB dose.

Branch D: Gecko hides constantly and rarely emerges

Constant hiding can indicate that the enclosure is too bright or that the gecko lacks adequate cover. Add dense foliage, cork bark, or artificial plants near the top and middle of the enclosure. If the gecko still hides, reduce the photoperiod to 10 hours and consider whether the UVB bulb output is appropriate. A 5% bulb may be too intense for a particularly shy individual, and switching to a 2% bulb may encourage more natural activity.

Branch E: Weight loss with normal appetite

Weight loss despite a normal appetite suggests the gecko is not digesting food properly, which is often temperature related. Measure the nighttime temperature. If it drops below 18 °C (65 °F), digestion slows significantly. Add a low-wattage ceramic heat emitter with a thermostat set to maintain 20 to 22 °C (68 to 72 °F) at night. Weigh the gecko weekly and record the trend. If weight loss continues for 4 weeks despite corrected temperatures, seek veterinary advice.

Step 4: Apply One Change at a Time

The most common error in troubleshooting is changing multiple variables at once. If you adjust the thermostat, replace the UVB bulb, and change the photoperiod on the same day, you cannot determine which change caused the improvement or the new problem. Apply one change, wait 7 days, and reassess using the observation score. This approach produces cleaner records and reduces the risk of introducing a new problem while solving an old one.

For example, if the gecko is lethargic and the UVB bulb is 14 months old, replace the bulb first and keep all other settings unchanged. Record the observation score before the change and again after 7 days. If the score improves, the bulb age was likely the cause. If the score does not improve, move to the next variable, such as photoperiod or temperature.

Step 5: Track Seasonal Adjustments

Crested geckos in the wild experience seasonal variation in temperature and day length. In captivity, a gradual seasonal adjustment can support normal physiological rhythms. During the cooler months, reduce the photoperiod to 10 hours and allow the nighttime temperature to drop to the lower end of the target range. During the warmer months, extend the photoperiod to 12 hours and allow the daytime temperature to rise to the upper end of the target range. Make these changes gradually over 2 to 3 weeks, not abruptly.

Record the seasonal settings in the log so that temperature readings are interpreted in context. A nighttime temperature of 19 °C (66 °F) in January is expected, while the same reading in July may indicate a heating failure.

Common Failure Patterns in the Adjustment Process

Several recurring mistakes undermine the decision framework. The first is relying on a single thermometer reading. Temperatures vary by location in the enclosure, and a reading at the cool end does not reflect conditions at the basking branch. Place thermometers at both ends and check them at the same time each day.

The second failure is ignoring bulb age. UVB output declines gradually, and a bulb that provided adequate UVB at 6 months may provide little at 14 months. Mark the replacement date on the bulb base and on the enclosure frame so it is visible during routine checks.

The third failure is making large changes in response to small variations. A single day of reduced activity does not warrant a setup change. Wait for a consistent pattern over 5 to 7 days before adjusting anything. This reduces the risk of overcorrecting and creating a new problem.

The fourth failure is neglecting the interaction between heat and UVB. A gecko that cannot reach its preferred temperature will not benefit from UVB exposure, because vitamin D synthesis and calcium metabolism depend on adequate body temperature. Always confirm that the thermal gradient is correct before evaluating whether UVB provision is adequate.

When to Escalate Beyond the Decision Framework

The decision framework addresses environmental causes of poor health, but not all problems are environmental. Escalate to veterinary care if the gecko shows any of the following despite a corrected setup: weight loss continuing for 4 weeks, swelling of the limbs or jaw, muscle tremors, open-mouth breathing, nasal discharge, or eye discharge that persists for more than 48 hours. These signs may indicate metabolic bone disease, respiratory infection, or another condition that requires professional diagnosis and treatment.

When consulting a veterinarian, bring the observation score records, temperature logs, bulb installation and replacement dates, and a description of the enclosure setup. This information allows the veterinarian to distinguish environmental causes from disease processes. The Merck Veterinary Manual provides general guidance on reptile examination and common conditions, and the Health and Welfare of Captive Reptiles, Second Edition offers a deeper reference for veterinary professionals managing reptile cases.

Frequently Asked Questions

Do crested geckos need UVB lighting?

Crested geckos can survive without UVB if their diet is properly supplemented with vitamin D3, but low-level UVB is beneficial and recommended. Research on a related lizard species, the blue-tongued skink, found that even 2 hours of UVB per day produced a significant rise in plasma vitamin D concentrations, while dietary vitamin D3 alone was insufficient to sustain those levels. See Measuring the Rise and Fall of Plasma 25-Hydroxyvitamin D Concentrations in Blue-Tongued Skinks Following Ultraviolet B Exposure and Withdrawal. A low-output 2% or 5% UVB bulb mounted at the correct distance provides a safety margin for vitamin D synthesis without forcing the gecko into bright light.

What is the best lighting for crested geckos?

The best lighting setup for crested geckos combines a low-output UVB bulb with a general light source on a timer. A 2% or 5% T5 linear fluorescent tube provides broad, even coverage and is preferred for larger enclosures. Compact fluorescent bulbs are acceptable for smaller enclosures. The UVB bulb should be mounted at the manufacturer's recommended distance, typically 20 to 30 cm (8 to 12 inches) from the basking area. A separate low-wattage LED or fluorescent light can provide illumination for the photoperiod and support live plants.

What lights do crested geckos need at night?

Crested geckos do not need any light at night. They are nocturnal and are naturally active in darkness. A consistent dark period is important for their circadian rhythm and overall health. If supplemental heat is needed at night, use a ceramic heat emitter, which produces heat without visible light. Red or blue night bulbs are not necessary and can disrupt the gecko's natural behavior.

How many hours of UVB do crested geckos need per day?

A reasonable starting point is 2 to 6 hours of UVB per day, or a low-output UVB bulb running for the full 10 to 12 hour photoperiod. The blue-tongued skink study found that 2 hours of UVB per day produced a significant rise in vitamin D concentrations, and that these levels remained above baseline for 4 months after UVB withdrawal. See Measuring the Rise and Fall of Plasma 25-Hydroxyvitamin D Concentrations in Blue-Tongued Skinks Following Ultraviolet B Exposure and Withdrawal. The exact duration for crested geckos has not been established, so observation and veterinary guidance should inform the final choice.

What temperature should a crested gecko enclosure be?

The daytime temperature should be 22 to 26 °C (72 to 79 °F), with a nighttime drop to 18 to 22 °C (65 to 72 °F). A gentle warm zone at the top of the enclosure can reach 26 to 28 °C (79 to 82 °F), but sustained temperatures above 28 °C (82 °F) are dangerous. A thermostat-controlled low-wattage heat source can maintain the gradient, and thermometers at both ends of the enclosure should be checked daily.

Can crested geckos get too much UVB?

Yes, excessive UVB exposure can cause eye damage, skin burns, and chronic stress. The risk increases when high-output bulbs are mounted too close to the basking area or when the gecko cannot escape the light. Providing dense foliage and hiding spots allows the gecko to self-regulate its exposure. A 2%

Related Veterinary Guides

• UVB Lighting for Reptiles: Ferguson Zones, Linear T5 Bulbs, and Metabolic Bone Disease Prevention
• Full-Spectrum Reef Aquarium LED Lighting: PAR Requirements, Coral Photosynthesis, and Spectrum Schedules
• Avian Full-Spectrum Lighting: UVA/UVB Synthesis, Flicker-Free Ballasts, and Calcium Absorption
• Crested Gecko Care Guide
• Crested Gecko Not Eating

References and Further Reading

• Merck Veterinary Manual. Merck Veterinary Manual.
• Animal Health and Welfare. World Organisation for Animal Health.
• Measuring the Rise and Fall of Plasma 25-Hydroxyvitamin D Concentrations in Blue-Tongued Skinks (&lt,i&gt,Tiliqua scincoides&lt,/i&gt,) Following Ultraviolet B Exposure and Withdrawal.. 2025.
• Case Report: Anesthesia for cloacal prolapse fixation surgery in an Argentine black and white tegu (&lt,i&gt,Salvator merianae&lt,/i&gt,).. 2026.
• Turtles for Sale: Species Prevalence in the Pet Trade in Poland and Potential Introduction Risks.. 2025.
• Effect of Racking Systems Versus Enriched Terraria on Fecal Glucocorticoid Metabolites in Four Species of Captive Snakes: A Pilot Study.. 2026.
• Human-Chelonian Bond in Italy: An Exploratory Study of Pet Turtle and Tortoise Ownership.. 2025.
• Health and Welfare of Captive Reptiles, Second Edition. 2023.
• A study of animal welfare in 11 species across 16 Zoos using M-AWAG and its correlations with environmental variables
• Keeping reptiles as pets in Brazil: keepers' motivations and husbandry practices.. 2023.
• Nocturnal LED Supplemental Lighting Improves Quality of Tomato Seedlings by Increasing Biomass Accumulation in a Controlled Environment. Agronomy, 2024.
• Effects of Different Nocturnal Lighting Stimuli on Melatonin, Sleep and Cognitive Performance of Workers in Confined Spaces. Buildings, 2023.
• Heat seekers: A tropical nocturnal lizard uses behavioral thermoregulation to exploit rare microclimates at night.. Journal of Thermal Biology, 2019.
• Division of Comparative Physiology and Biochemistry , Society for Integrative and Comparative Biology Low Cost of Locomotion Increases Performance at Low Temperature in a Nocturnal Lizard. 2017.

This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.